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IHO > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Hematopoiesis

A

• Process of the generation of cellular components of blood from hemopoietic stem cells
• mesodermal, derived, except thymus, which is endoderm

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2
Q

Purpose of hemopoietic tissue

A

• makes new blood cells
• removes old/worn out cells

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3
Q

Myeloid tissue

A

• produces most blood cell types
• bone marrow
• common myeloid progenitor (CMP)

CMP –> granulocyte progenitor –> neutro, baso, eosino, monocyte/macrophage

CMP–> erythro/megakaryo progenitor –> RBC/ platelet

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4
Q

Lymphoid tissue

A

• abundance of lymphocytes
• responsible for immune defenses of the body
• sinus, lymph nodes, spleen, non-encapsulated lymph nodules
• common lymphoid progenitor (CLP)

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5
Q

Hemopoietic, tissue forms what?

A
  1. White blood cells. (leukopoiesis) via lymphopoiesis, Myelopoiesis and granulopoiesis
  2. Platelets (thrombopoiesis.), megakaryocytopoiesis
  3. Red blood cells (erythropoiesis)
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6
Q

Hematopoiesis progression with age

A

1.) yolk sac, six weeks
2.) liver, six weeks-five months
3.) spleen, three months-eight months
4.) lymph nodes, four months-lifelong
5.) bone marrow, four months-lifelong
6.) thymus, four months-lifelong

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7
Q

Yolk sac

A

• 1st/primitive hematopoiesis
• endothelial cells—> primitive vessels
• undifferentiated, pluripotent stem cells

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8
Q

Liver

A

• major sight of blood formation until mid fetal life
• erythropoiesis dominates here (extravascularly)
• RBCs nucleated at seven weeks, non-nucleated by the 11th week

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9
Q

Spleen

A

• hematopoiesis in the third fetal month
• erythropoiesis and granulopoiesis reach peak between third and fifth fetal months and last until the seventh/8th fetal month
• lymphopoiesis continues throughout life

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10
Q

What bone is the first one to develop a medullary cavity?

A

The clavicle— myeloid cell development

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11
Q

Thymus

A

• lymphopoiesis only
• begins in the fourth fetal month
• T lymphocytes formation

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12
Q

Extra medullary myelopoiesis

A

• pathological condition
• development of myeloid tissue outside of the bone marrow
• liver, thymus, and spleen may large

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13
Q

Yellow bone marrow

A

• contains more adipocytes
• occupies much of diaphysis of long bones
• most bone marrow in adults is yellow, amount increases with age
• contain stem cells and converts to red marrow to generate blood cells

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14
Q

Red bone marrow

A

• contains more hemopoietic cells than adipocytes
• site of hematopoiesis
• amount decreases with age
• found in the skull, ribs, sternum, vertebral bodies, cancellous, bone, long and short bones, iliac crest in adults

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15
Q

What are the components of bone marrow?

A
  1. Stroma (connective tissue)
  2. Sinusoids
  3. Developing blood cells
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16
Q

Stroma of the bone marrow

A

• cells: fibroblasts, macrophages, adipocytes, osteogenic cells, endothelial cells
• generate growth factors that regulate hematopoiesis
• contains collagenous and reticular fibers

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17
Q

Sinusoids of the bone marrow

A

• contains sinusoidal capillaries
• endothelial cells, endothelial, stem cells
• connect arterial to venous side of circulation
• permit, red and white cells to enter circulation via diapedesis (continuous, fenestrated, sinusoid)

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18
Q

Erythropoietin

A

• reduced in the kidney and other sites
• induced by hypoxia
• increases the number of hemoglobin forming cells by stimulating stem cells (CFU-E)

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19
Q

Erythropoiesis

A

• RBC development in the bone marrow
• cytoplasm: basophilic—> eosinophilic
• nucleus: light to dark, fine chromatin—> clumped chromatin, large—> small—> gone

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20
Q

Erythropoiesis must be balanced by what?

A

• RBC destruction in the spleen and bone marrow

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21
Q

When do erythrocytes become non-mitotic in development?

A

• orthochromatophilic erythroblast
• reticulocyte
• mature, erythrocyte

• all of these are eosinophilic

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22
Q

Where in the body will you find most of the reticulocytes?

A

In the peripheral blood

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23
Q

Granulopoiesis

A

• granulocyte development in the bone marrow
• cytoplasm: basophilic—> eosinophilic
• specific granules gradually increasing number
• azurophilic granules, gradually decrease in number
• nucleus: round—> polymorphonuclear
• nucleoli: present—> gone

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24
Q

How long does Granulopoiesis take?

A

Around 14 days. Circulates in the peripheral blood for around 6 to 10 hours. Once they leave the vascular system, they function in the connective tissue for one to six days.

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25
Q

Monopoiesis

A

• the development of monocytes
• CMP—> monoblast—> promonocyte—> monocyte—(in tissue)—> macrophage

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26
Q

Thrombocytopoeisis

A

• platelet formation in the bone marrow
• involves the giant nucleated cell: megakaryocyte
• nucleus undergoes endomitosis: copies, and enlarges DNA, but does not divide cytoplasm
• cytoplasm fragments into thousands of platelets

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27
Q

Where will you find a megakaryocyte?

A

They live by the sinusoids in order to send platelets into circulation

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28
Q

Types of hematopoietic tissue

A
  1. Myeloid tissue
    • produces most blood cell types
    • bone marrow
    • common myeloid progenitor (CMP)
  2. Lymphoid tissue
    • abundance of lymphocytes
    • responsible for immune defenses of the body
    • thymus, lymph nodes, spleen, non-encapsulated lymph nodules
    • common lymphoid progenitor (CLP)
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29
Q

Lymphopoiesis

A

• B lymphocytes develop in bone marrow and spleen
• T lymphocytes develop in bone marrow before maturing in the thymus
• mature B & T lymphocytes populate other secondary lymphatic organs
• CLP—> lymphoblast—> prolymphocyte—> B cells, T cells, NK cells

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30
Q

Central (primary) location of lymphatic tissue

A

• bone marrow: B cells
• thymus: T cells

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31
Q

Location of peripheral (secondary) lymphatic tissues

A

• mucosa associated lymphatic tissue (nodular, non-encapsulated lymphatic tissue). Ex: tonsils, digestive, tract, respiratory, urinary, reproductive tracts
• lymph nodes (encapsulated)
• spleen (encapsulated)

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32
Q

Lymphatic tissue characteristics

A

• populated with lymphocytes
• large lymphocytes: activated, NK cells
• small lymphocytes: B cells, T cells

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33
Q

Functions of lymphatic tissues

A

• lymphopoiesis
• immune response: small lymphocytes (recirculate between blood and lymph, capable of responding to antigen)

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34
Q

Stromal cells

A

• a component of lymphoid tissues
• reticular cells (specialized fibroblasts)
• macrophages (antigen, presenting cells)
• dendritic cells (APCs— very efficient)
• follicular dendritic cells (mesenchymal, not APCs)

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35
Q

Non-encapsulated lymphatic tissues

A

1.) diffuse, lymphatic tissue found in GI, respiratory, urinary, reproductive.
• loose or dense

2.) nodular lymphatic tissue found in GI, respiratory, urinary, reproductive.
• represent local immune responses to antigens, characterized by solitary lymphatic nodules

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36
Q

Lymphatic nodules

A

• not enclosed by a capsule
• primary: dark staining spherical balls of lymphocytes
• secondary: contain a reaction (germinal) center

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37
Q

General features of secondary lymphatic nodules

A

• germinal center indicates response to an antigen (T cell mediated)
• immature B cell proliferation (larger cytoplasm makes it stain lighter in the center)
• antibody production by plasma cells
• accumulation of macrophages and follicular dendritic cells

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38
Q

Where do you find aggregates of lymphatic nodules?

A
  1. Non-encapsulated lymph nodules
  2. Tonsils of oropharynx
  3. Peyer’s patches (ileum of small intestine)
  4. Appendix
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39
Q

Functions of lymphatic nodules

A
  1. Trapping of antigen
  2. Lymphocyte production in response to antigen: B cell proliferation
  3. Destruction of antigen
  • no afferent lymphatic vessels
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40
Q

Lymph node

A

• only lymphatic organ located in the course of lymphatic vessels
• only lymphatic organ that has lymphatic sinuses
• only lymphatic organ that filters lymph (done by macrophages)

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41
Q

Morphological features of lymph nodes

A
  1. Capsule (dense CT)
  2. Trabeculae (dense CT)
  3. Stroma (cells and fibers, reticular)
  4. Endothelial cells: line sinusoids
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42
Q

What is in the cortex of a lymph node?

A

• lymphoid tissue, supported by reticular fibers and stromal cells
• lymphocytes
• lymphatic, nodules, including germinal centers, and tails that extend into the medulla as medullary cords

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43
Q

What is in the medulla of the lymph node?

A

• lymphoid tissue, supported by reticular fibers and stromal cells
• medullary cords and sinuses
• cells: small lymphocytes
• sinuses converge near hilum and drain into efferent lymphatic vessels

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44
Q

Superficial cortex of a lymph node

A

• between capsule and inner limits of germinal centers
• contains majority B cells

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45
Q

Deep cortex (paracortex) of a lymph node

A

• between germinal centers and medullary cords
• majority T cells

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46
Q

Lymph node sinuses

A

• lined by endothelial cells with large intercellular gaps
• slow, lymph flow- can trap metastatic cancer cells
• lymphocytes, enter lymphatic sinuses and leave lymph node via efferent lymphatics at hilus

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47
Q

Direction of lymph flow

A

Afferent lymphatic vessels—> subcapsular sinus—> trabecular sinus—> paracortical sinus—> medullary sinus—> efferent lymphatic vessel—> aorta

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48
Q

Post capillary venules in lymph node

A
  1. Outer superficial cortex: simple, squamous endothelium
  2. Deep paracortex: simple cuboidal endothelium, high endothelial venule (HEVs)
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49
Q

High endothelial venule (HEV)

A

• site of passage of lymphocytes from blood vessels into lymphatic tissue
• allow physical contact between APC and lymphocytes for activation— adaptive immune responses

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50
Q

Pathway of blood flow for lymphocytes

A

afferent arterioles—> precapillary arterioles—> capillaries—> HEVs—> lymphatic tissue—> lymphatic sinuses—> efferent, lymphatic vessels

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51
Q

What are the functions of the lymph nodes?

A

• lymph filter by macrophages
• lymphocyte production
• antibody production (plasma cells)

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52
Q

Anatomical and physiological barriers for antigens

A

• intact skin
• ciliary lung clearance
• stomach PH
• lysozymes in tears and saliva and ear wax

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53
Q

Innate immunity against antigens

A

• natural killer cells
• eosinophils
• macrophages
• mast cells
• neutrophils
• complement
• C reactive protein
• antimicrobial peptides
• dendritic cells
• natural killer cells

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54
Q

Adaptive immunity against pathogens/antigens

A

• T cells, B cells
• Humoral- antibodies
• dendritic/natural killer

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55
Q

Innate immune response

A

•Fast, generally nonspecific reaction to foreign antigens
• pattern, recognition receptors
• complement cascades

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56
Q

Adaptive immune response

A

• antigen specific response (B cell—> antibodies, T cell—> B cell helpers, and cytotoxicity/killing)
• long term protective immunity

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57
Q

All immune progenitor cells first originate, where?

A

In the bone marrow—> hematopoietic stem cell—> myeloid progenitor cell (innate), and lymphoid progenitor cell (adaptive)

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58
Q

Natural killer cells:

A

Are classified as innate because they are fast, primed, and ready. However, they come from a lymphoid progenitor cell, which is typically adaptive.

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59
Q

Major roles of natural killer cells

A

• protection in infected, stressed, and cancer cells
• they are stimulated by innate cytokines
• they are potent IFN-gamma and TNF-alpha producers
• NK receptors function as kill or do not kill switches

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60
Q

How is natural killer cells killing initiated?

A

Absence of self recognition. The presence of an activating signal will always be overridden by an inhibitory signals in the NK cell.

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61
Q

The two mechanisms natural killer cells use to kill

A
  1. Granule-mediated: granzyme B (serine protease), perforin (oligomeric pore forming protein) — must be close contact
  2. Death receptor-mediated: Fas:FasL, or TRAIL R:TRAIL

• both involve apoptosis induction, programmed cell death

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62
Q

IL1

A

• fever, acute inflammation, endothelial expression adhesion molecules, chemokine secretion (WBC recruitment)

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63
Q

IL4

A

• induces, differentiation, and proliferation of Th2 helper cells. Class switching of IgM to IgE. Role in class one hypersensitivity reaction.

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64
Q

IL6

A

• fever, and acute phase protein production

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65
Q

TNF-alpha

A

• endothelial, activation, WBC, recruitment, vascular, leaking us, fever
• cachexia in cancer, granuloma, maintenance in TB

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66
Q

IL8

A

Neutrophil chemotactic factors— cleanup on aisle eight. Clear infections.

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67
Q

IL12

A

NK cell activation, Th1 differentiation
- Granuloma formation in TB

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68
Q

IFN- alpha/beta

A

• innate defense against viruses via inhibition of protein synthesis, and induces ribonuclease to degrade mRNA. Activates NK cell killing functions.

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69
Q

Which cytokines are secreted by macrophages, dendritic cells, monocytes?

A

• IL1
• IL4
• IL6
• TNF- alpha
• IL8
• IL12
• IFN alpha/beta

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70
Q

Which cytokines are secreted by T cells?

A

• IL2: supports proliferation and differentiation of T cell, subsets and NK cells
• IL3: supports growth and differentiation of bone marrow stem cells

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71
Q

Cytokines secreted by TH1/NK cells

A

IFN-gamma: produced in response to IL12, induces, macrophage, killing of phagocytosis pathogens. Induces IgG isotope switching inhibits Th2 differentiation

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72
Q

cytokines secreted by Th2

A

• IL4
• IL5
• IL10: Tregs to dampen immune response
* IL11
• IL13

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73
Q

PRR: remembering associated receptors

A

• extracellular, or lysosomal recognition
• TLRs
• c-type lectin receptors (CLRs)

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74
Q

PRR: cytoplasmic receptors

A

• intracellular recognition
• nucleotide-binding and oligomerization domain-like receptors
• inflammasome
• RIG-l like (RLRs), CCR7

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75
Q

Complement cascade summary

A

• early control, and clearance of infectious pathogens the serum and membrane bound proteins
• alternative, classical, lectin
• all pathways converge at cleavage of C5
• form membrane attack complex for osmotic cell lysis

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76
Q

What helps leukocytes come out of the vasculature, into the tissue?

A

Selectins and integrins: adhesion molecules, that aid in leukocyte recruitment

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77
Q

Innate immune response: virus

A

NK cells—> target lysis. Killing via Fas:FasL, TRAIL

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78
Q

Innate immune response: bacteria

A

Macrophage/dendritic cell—> phagocytosis—> antigen, uptake, and presentation—> cytokine production—> chemotaxis

Complement —> osmotic lysis of bacteria

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79
Q

Humoral mediated immunity

A

• antibody mediated
• B lymphocytes
• antibodies, circulating in serum
• primary defense against extracellular pathogens: bacteria and circulating viruses

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80
Q

Cell mediated immunity

A

• cell mediated
• T lymphocytes
• direct cell to cell contact or secreted soluble products (cytokines)
• primary defense against intracellular pathogens: viruses and fungi, intracellular bacteria, tumor antigens, and graft rejection

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81
Q

What complex tells a T cell whether a cell or tissue is self versus nonself?

A

Major histocompatibility complex

MHC1: T cells B cells, macrophages, dendritic cells, neutrophils

MHC2: B cells, dendritic cells, epithelial cells of thymus

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82
Q

Positive selection

A

Only T cells with TCR recognize self-MHC survive

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83
Q

Negative selection

A

T cells that react to strongly to self-MHC are eliminated

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84
Q

Which cells do antigen presentation to activate T cells?

A

• dendritic cells
• macrophages
• Thymic epithelial cells, and B cells

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85
Q

Why are dendritic cells very efficient antigen presenting cells (APCs)?

A

• they are located in a common site of entry for foreign antigens
• they express receptors that allow capture of antigens and processing of antigenic peptides
• they express high levels of peptide MHCs, co-stimulatory molecules, and produce cytokines
• they can present antigen and needed signals to both CD4 and CD8 T cells

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86
Q

Macrophages are:

A

Resident tissue APCs. They like to stay right at home.

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87
Q

Dendritic cells are:

A

In tissue but traffic to the lymph node: traveling salesman, displaying their goods

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88
Q

T cell activation: two signals

A
  1. MHC
  2. Co- receptor binding

• both signals are required. If only one signal, the T cell becomes anergic and non-responsive to the antigen

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89
Q

Th1

A

• IFN-gamma
• macrophages
• macrophage activation
• intracellular pathogens
• autoimmunity, chronic inflammation

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90
Q

Th2

A

• IL4, IL5, IL13
• eosinophils
• eosinophil and mast cell activation, alternative macrophage activation
• helminths
• allergy

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91
Q

Th17

A

• IL17, IL22
• neutrophils
• neutrophil, recruitment, and activation
• extracellular, bacteria, and fungi
• autoimmunity, inflammation

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92
Q

Tfh

A

• IL21, IFN-gamma, IL4
• B cells
• antibody production
• extracellular pathogens
• autoimmunity (autoantibodies)

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93
Q

B cell maturation: self tolerance

A
  1. Receptor editing: replacement of self reactive, receptor with nonself reactive receptor
  2. Clonal deletion: elimination of self reactive B cell clones
  3. Clonal anergy: an antigen specific hypo responsiveness
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94
Q

What is an epitope?

A

The specific molecular target of which a complementary antibody binds to

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95
Q

How do you yield high affinity antibody of a distinct isotope?

A

Somatic hypermutation, affinity maturation, and class switching

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96
Q

Which antibodies are multimeric?

A

IgA: dimer
IgM: pentamer

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97
Q

T cell independent B cell mechanisms

A
  1. Neutralization.
  2. Opsonization
  3. Complement activation
  4. Antibody dependent cellular cytotoxicity (ADCC)
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98
Q

T cell dependent B cell activation

A
  1. Activated helper T cell expresses CD40L, secretes cytokines
  2. B cells are activated by CD40 engagement, cytokines
  3. B cell proliferation and differentiation
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99
Q

Type one hypersensitivity: immediate

A

• IgE, CD4+, Th2
• allergy, anaphylaxis, atopic
• mast cells, eosinophils
• IL4, IL5, IL13

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100
Q

Type two hypersensitivity: antibody mediated

A

• IgM, IgG against cell surface or extracellular matrix proteins
• cellular destruction: opsonization, complement, ADCC, inflammation

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101
Q

Type three hypersensitivity: immune complex mediated

A

• circulating, antigen antibody complexes
• complement activation
• neutrophil, attraction, and lysozyme release
• Ab:Ag bulky

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102
Q

Type four hypersensitivity: delayed, T cell mediated

A

• CD4+, CD8+, Th1, Th17
• cytokine mediated inflammation, macrophage, neutrophil, activation (CD4+)
• direct target cell killing (CD8+, CTLs)

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103
Q

B cell coreceptors required for activation

A

• CD21
• CD19
• CD3

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104
Q

T cell coreceptors required for activation

A

• CD80/86
• CD28
• CD3- intracellular signal motif

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105
Q

PLC pathway

A

TCR—> PLCgamma1—> calcineurin—> NFAT —> activation IL2—> T cell proliferation control

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106
Q

Cyclosporine

A

An immunosuppressant that is used to treat both T cell mediated, Auto immune disease and organ transplant Rejection. Acts by blocking the function of calcineurin. Prohibits T cell interaction with antigen.

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107
Q

Ras/MAP pathway

A

This kinase cascade activates gene transcription through AP-1

Raf (MAPKKK) —> MEK (MAPKK) —> ERK (MAPK)

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108
Q

PKC pathway

A

• activates transcription through NF-kB (important in many innate and adaptive immune processes- associated with pro-inflammatory an activation events rather than regulatory processes)

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109
Q

Cytokines

A

Secreted, low molecular weight proteins that regulate the immune response by exerting effects on cells that express the appropriate receptor. Typically cell to cell signaling.

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110
Q

Chemokines

A

• Cytokines that mediate chemotaxis in particular leukocytes via receptor engagement. Can regulate the expression, and/or adhesiveness of leukocyte integrins.
• chemoattractants

• chemokines: CCL(#), CXCL(#), XCL1, CX3CL1
• chemokine receptors: CCR(#), CXCR(#), XCR1, CX3CR1

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111
Q

Cytokine spatial function

A
  1. Endocrine: far away cell, through circulation
  2. Paracrine: nearby cell
  3. Autocrine: self
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112
Q

Pleiotropic

A

Induces different biological effects, depending on the nature of the target cell type

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113
Q

Redundant

A

Two or more cytokines that mediate similar function

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114
Q

Synergy

A

Combined effect of two cytokines on cellular activity is greater than the additive effect of the two cytokines

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115
Q

Antagonize

A

The effect of one cytokine cancels out the effect of another

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116
Q

Cascade induction

A

The effect of one cytokine on a target cell leads to the production of one or more additional cytokines from that target cell

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117
Q

Interferons (IFNs)

A

Cytokines that are important in limiting the spread of viral infections

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118
Q

Interleukins (ILs)

A

Large group of cytokines produced, mainly by T cells. Variety of functions, including causing neighboring cells to divide and differentiate.

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119
Q

Colony stimulating factors (CSFs)

A

Primarily involved in directing the division and differentiation of bone marrow, stem cells and precursors of blood leukocytes. Controls how many and what kind of leukocyte is to be produced

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120
Q

Chemokines

A

Chemotactic cytokine used to direct the movement of leukocytes around the body

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121
Q

Tumor necrosis factors (TNFs)

A

Particularly important in mediating inflammation and cytotoxic reactions

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122
Q

Transforming growth factors (TGFs)

A

Important in regulating cell division, and tissue repair

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123
Q

If you lose the common gamma chain:

A

You will lose signaling from multiple cytokines important in T cell development, B cell and NK cell development, class switch recombination, and homeostasis
(IL21, 15, 9, 7, 4, 2)

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124
Q

Variable region

A

Area of the antibody where antigen binds

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125
Q

Hinge region

A

Part of the heavy chain of an antibody that has flexibility. It’s normal confirmation hides the compliment binding site to prevent unwanted, complement activation. Once antigen has been bound, it will open in this area and allow for immune response.

126
Q

Antibody structure of IgG

A

Light chain: one variable domain, and one constant domain

Heavy chain: one variable domain, and 3-4 constant domains

(x2)

127
Q

Antibody structure: IgM

A

• pentamer— connected by a J chain

Light chain: one variable, one constant

Heavy chain: one variable 4 constant

128
Q

Antibody structure: IgA

A

• dimer— connected by a J chain

Light chain: one variable, one constant

Heavy chain: one variable, one constant

129
Q

Antibody structure: IgD

A

• membrane bound on B cells (like IgM)
• has tail pieces that have two more Constants on them. Hinge region is in between the normal chain and the tail pieces.

Light chain: one variable, one constant

heavy chain: one variable, one constant

130
Q

Antibody structure: IgE

A

• monomer

Light chain: one variable, one constant

Heavy chain: one variable, four constant

131
Q

Light chain varieties:

A

Kappa or Llamada. It may use one or the other, cannot use both. It does allow for flexibility during the cell modification. When class switching, the heavy chain gets replaced, but the light chain always stays the same.

132
Q

Isotypes

A

• on the basis of slight differences in the amino acid, sequences of their H chain C regions. The five main classes of immunoglobulins are divided into sub classes based off of our genome

  1. IgG: 1,2,3,4
  2. IgA: 1,2
  3. IgM: 1,2
  4. IgD: 1
  5. IgE: 1
133
Q

Allotypes

A

• minor allelic differences in the sequence of immunoglobulins between individuals
• determined by your parents in the usual Mendelian fashion
• this is why we used pooled immunoglobulin serum for infusions

134
Q

Idiotypes

A

• each antibody will have a unique combining region made up of the hyper variable amino acids of its L & H chains.

135
Q

B cells protect:

A

The extra cellular spaces of the body— the tissue, fluids, blood, secretions by releasing antibodies into the fluids (humoral immunity)

136
Q

T cells:

A

Themselves survey the surface of the bodies sells looking for ones that have been changed or mutated (cell mediated immunity)

137
Q

Antibody diversity is generated during:

A

• Genetic rearrangement by mixing and matching one of each of the various genes segments for the heavy and light chains in a combinatorial matter
• variation incorporated at the joining sites for the various segments of the heavy in light chains
• hyper mutation in one of the gene segments of the heavy and light chains during proliferation of B cells
• mixing, and matching heavy and light chains in a combinatorial manner

138
Q

RAG 1/2 protein involved in VDJ recombination

A

Lymphoid specific complex of two proteins, that catalyze DNA strand breakage and re-join to form signal and coding joints

139
Q

TdT protein involved in VDJ recombination

A

Lymphoid specific protein that adds N region nucleotides to the joints between gene segments in the Ig heavy chain, and at all joints between TCR gene segments

140
Q

HMG 1/2 protein involved in VDJ recombination

A

Stabilize binding of RAG 1/2 to recombination signal sequences, particularly to the 23-bp RSS. Stabilized and introduced into the 23-bp spacer DNA by the RAG 1/2 proteins

141
Q

Ku70 and Ku80 heterodimer protein involved in VDJ recombination

A

Binds DNA coding and signal ends and holds them in protein-DNA complex

142
Q

DNA PKcs protein involved in VDJ recombination

A

In complex with Ku proteins, recruits and phosphorylates Artemis

143
Q

Artemis protein involved in VDJ recombination

A

Opens the coding end hairpins

144
Q

XRCC4 protein involved in VDJ recombination

A

Stabilizes and activates DNA ligase IV

145
Q

DNA ligase IV protein involved in VDJ recombination

A

In complex with XRCC4, and cernunnos. Ligates DNA ends.

146
Q

Cernunnos protein involved in VDJ recombination

A

With XRCC4, activates DNA ligase IV

147
Q

VH domain gene is composed of:

A

One V, one D, and one J

Light chain: V, J
Heavy chain : V, D, J

148
Q

How to make heavy chains:

A

D + J —> DNA cut, ends joined —> V + DJ —> DNA cut, ends joined

Primary RNA transcripts are alternatively processed using alt polyA sites and splicing

149
Q

How to make light chains

A

Gene rearrangement, but only with V and J segments, and only one constant gene domain. There is a kappa and lambda chain, while one is transcribed the other is silenced

150
Q

The enzymes that do the recombination of antibody and T cell receptor DNA are called:

A

RAG1 and RAG2 recombinases.

They first bind splice signals to the right of a DNA segment and the left of a J segment, pull them together, and then cut and splice.

If RAGs are knocked out, B and T cells fail to form

151
Q

Diversity through somatic variation

A
  • sloppy
  • exonucleases chew away a few nucleotides after the DNA is cut but before two gene segments are joined. Therefore N region (where they are joined) is unpredictable
  • 2/3 times this does not work because it does not add/cut in lengths of 3 so there are frameshift mutations and nonsense codons that terminate transcription
152
Q

Receptor editing

A
  • If a rearrangement is detected as faulty, the RAG genes are still active and can “try again” which sometimes results in a successful cell.
153
Q

Mature but not activated B cells initially express:

A

IgD and IgM on their external surfaces

154
Q

As mature B cells are activated to divide and differentiate by their cognate antigen, they switch from:

A

membrane bound IgM and IgD to secretory IgM. This occurs at the level of processing of mRNA transcripts

155
Q

Affinity maturation

A

Selection of the best fitting mutants after antigenic stimulation allows a gradual increase of affinity during an immune response

156
Q

Somatic hypermutation

A

Activation- induced (cytidine) deaminase (AID) converts random cytosines in the variable gene regions to a uracil. C:G pair becomes a mismatch, and DNA polymerases come and fix it and replace it with single-base substitution mutations that may make the cell a better/worse antibody.

157
Q

Class switching

A

Stay the same: L chain, and VH domain

Changes: C region of the H chain

– when the switch occurs, the DNA for the previous IgM/IgD gets excised, therefore you cannot go back once you go forward.

158
Q

What are the functions of blood?

A
  1. transport gases, hormones, nutrients, and waste products
  2. regulates body temperature
  3. protects against pathogens and fluid loss
159
Q

Major cation in plasma

160
Q

Major anion in plasma

A

Chloride and bicarbonate

161
Q

What is serum?

A

The acellular liquid fraction after blood has been allowed to clot (HAS NO FIBRINOGEN)

  • THINK: fibrinogen is all taken up in the clots so you will no see it.
162
Q

In the starved state, how are fatty acids transported from adipose tissue to the liver?

A

As fatty acids bound to albumin

163
Q

Paclitaxel

A

Breast cancer treatment that affects microtubule stabilization, acting on M phase of the cell cycle and the microtubules cannot pull apart the dividing chromatin (no cell division). Can be carried into the cells by albumin

164
Q

Where is albumin synthesized and found primarily?

A
  • synth: by hepatocytes
  • excreted into blood
  • Found: in the interstitial space
165
Q

What is the most abundant protein in plasma?

A
  • Albumin

Functions of albumin: Transportation, oncotic pressure regulation, antioxidant effects

166
Q

What is transported by albumin?

A

Endogenous substances: Fatty acids (up to 7 at a time), steroids, L-tryptophan, copper, bilirubin, calcium, zinc

Drugs: Warfarin, chlorpromazine, ibuprofen, naproxen

167
Q

What is the main receptor for albumin?

A

Albondin (gp60)

168
Q

Albumin bound paclitaxel works best for what breast cancer?

A

triple negative breast cancer ( basal subtype found in younger, more aggressive type)

169
Q

Oncotic pressure

A
  • The contribution of dissolved colloids to osmotic pressure. In plasma, albumin contributes to 75% of the total oncotic pressure.
  • maintaining pressure is critical for filtering out fluid from the circulatory system and into lymphatic vessels in capillary beds.
170
Q

Kwashiorkor

A
  • protein malnutrition
  • Prominent feature: swollen belly, edema, relating to albumin effects of oncotic pressure
171
Q

On the arterial side of a capillary:

A

hydrostatic pressure exceeds oncotic pressure and fluid leaves the capillary

172
Q

On the venous side of a capillary:

A

Oncotic pressure exceeds hydrostatic pressure and fluid enters the capillary

173
Q

Hypoabluminemia

A
  • loss of oncotic pressure leading to interstitial edema. Rapid loss of fluid from the vasculature, with no way for reentry.
174
Q

What makes albumin a good antioxidant?

A
  • exposed cysteines
  • the sulfur from Cys34 can be oxidized by reactive oxygen species
  • albumin also binds and sequesters copper (source of oxidative stress)
175
Q

What is the buffer in a hepatic cell?

A

HPO4 2- accepting proton

PR accepting proton

176
Q

What is the buffer in the blood?

A

HCO3- from RBC via chloride antiporter

177
Q

What is the buffer in an RBC?

A

Hb (hemoglobin)

HPO4 2-

178
Q

Things that physiologically regulate hemoglobin’s affinity for oxygen (add to Bohr effect)

A
  1. Hydrogen ions
  2. 2,3-BPG
  3. Covalent binding of CO2
179
Q

Bohr effect:

A

as pH decreases, hemoglobin’s affinity for oxygen decreases and oxygen saturation decreases

180
Q

How is 2,3-BPG produced?

A

Through the Rapport-Luberin shunt via a mutase enzyme for 1,3-BPG and a phosphatase enzyme to 3-PG

181
Q

Rate limiting step in glycolysis

A
  1. Phosphofructokinase-1
  • activated by: AMP, fructose 2,6-BP
  • inhibited by: ATP, citrate
182
Q

What is the most important function of NADPH in red blood cells?

A
  • Glutathione reduction
183
Q

People with glucose 6-phosphate deficiency experience what?

A

Hemolytic anemia in response to acute oxidative stress. This is because they cannot produce NADPH and therefore cannot produce reduced glutathione

184
Q

What converts Fe3+ back to Fe2+ using the reducing power of NADH derived from glycolysis?

A

Cytochrome-B5 methemoglobin reductase

MetHbFe3+ seen with benzocaine anesthetic and G6PD

185
Q

If methemoglobin accumulates:

A

It will condense into dark inclusions visible within erythrocytes called Heinz bodies. Bite cells can also occur

186
Q

When does methemoglobinemia occur?

A

when the production of methemoglobin exceeds the reducing power of the erythrocyte. –> hypoxia, cyanosis, death

Treatment: Methylene blue ( electron acceptor in the NADPH methemoglobin reductase reaction)

187
Q

Newtonian fluid

A

Deformation of the fluid is proportional to the stress applied to it. (ex. water and plasma)

  • Blood is non-newtonian because it is more resistant to movement from small forces than large forces
188
Q

What is the key determinant of blood viscosity?

A

Amount of red blood cells

189
Q

Cytokine receptors are:

A

JAK/STAT receptors. Ligand binding causes JAKs to phosphorylate the receptors, recruiting STAT proteins which dimerize, translocate to the nucleus, and activate transcription of target genes

190
Q

What dampens the signal of cytokines?

A

SOCS expression

191
Q

Target genes of erythropoietin receptor

A
  1. Bcl-XL (anti-apoptotic)
  2. cyclin D (G1-S checkpoint)
192
Q

What is a mutation in JAK2 that makes the erythropoietic system constitutively active causing an inappropriately high signal from erythropoietin?

A

Polycythemia

193
Q

Polycythemia vera

A

a disease caused by overproduction of red blood cells. The increased viscosity of blood increased the risk for thrombosis

  • typically sporadic somatic mutation, rarely inherited
194
Q

Treatment for polycythemia vera

A
  1. phlebotomy
  2. Hydroxyurea (inhibits ribonucleotide reductase and inhibits hematopoiesis)
195
Q

Thymus

A
  • no afferent lymphatic vessels
  • efferent lymphatic vessels in capsule and CT
  • site for differentiation of T cells
  • largest in fetal life and gets smaller over time
  • Endodermal epithelial cells –> epithelioreticular cells and Thymic (Hassall’s corpuscles)
196
Q

The thymus is colonized by

A

Common lymphoid progenitor cells (CLP)

197
Q

Morphological features of the thymus

A
  • Two lobes enclosed by CT capsule (divided by CT trabeculae or septae)
  • between sternum/heart
  • Cortex and medulla within each lobe
198
Q

Thymus staining of cortex and medulla

A

Cortex: stains darker

Medulla: stains lighter, thymic corpuscles in medulla (round, eosinophilic)

199
Q

Cells of the Thymus cortex:

A
  1. Epithelioreticular cells
  2. Macrophages
  3. Lymphocytes (various stages of maturation)

– No CT or reticular fibers in the cortex

200
Q

Epithelioreticular cells

A
  • interconnected processes form a closely packed cellular network that supports and forms a barrier around the differentiating t-cells
  • large, faintly stained nucleus
  • do not produce reticular fibers
  • express MHCI and MHCII
    -APCs to thymocytes for education
  • produce thymic hormones
  • helps form blood-thymus barrier with desmosomes
201
Q

Macrophages in the thymus cortex

A
  • phagocytic
  • destroys abnormally developing T cells
  • Stained with PAS (periodic acid ship staining) because they do not stain with H&E
202
Q

What makes up the medulla of the thymus?

A
  • epithelioreticular cells
  • larger lymphocytes (more differentiated)
  • some connective tissue cells and reticular fibers
  • Thymic corpuscles (Hassall’s- concentric wrapped epithelioreticular cells)
203
Q

What is one thing that thymic corpuscles do?

A
  • regulate dendritic selection of a specific lineage of T cells (FoxP3+)
204
Q

Thymus vascular supply

A
  • internal thoracic and inferior thyroid arteries
205
Q

Blood thymus barrier

A
  • prevents antigens in blood stream from entering the thymic cortex
  • Components: endothelial cells with tight junctions, basal lamina, perivascular CT, epithelioreticular cells with desmosomes
206
Q

Spleen

A
  • largest lymphatic organ
  • no afferent lymphatic vessels
  • efferent lymphatic vessels present
  • no lymph sinuses
207
Q

Hilus of the spleen

A
  • artery and vein
  • efferent lymphatic vessels
  • sympathetic nerve fibers
  • thick capsule with some smooth muscle
  • thick CT trabeculae
  • splenic pulp, white and red
208
Q

White splenic pulp

A
  • occupied by lymphoid cells
  • periarterial lymphatic sheath (PALS) surrounding white pulp artery
  • contains primarily T cells
  • Splenic lymphatic nodules - scattered throughout length of the PALS
  • contains primarily B cells
209
Q

Red pulp

A
  • occupied by myeloid cells
  • splenic sinuses (sinusoids)
  • Splenic cords (billroth cords)
210
Q

Splenic sinusoids

A
  • vascular passageways lined by specialized endothelial cells
211
Q

Splenic cords

A
  • located between sinuses
  • contains: RBCs, granulocytes, lymphocytes, macrophages, dendritic cells, plasma cells, reticular cells and fibers
212
Q

Red pulp marginal zone

A
  • zone between the red and white pulp
  • small blood vessels dump their blood into this area (slow flow rate)
  • traps antigen for presentation to lymphocytes
  • macrophages help to clear antigen by phagocytosis
213
Q

Sinusoids of the spleen

A
  • consist of elongated and narrow endothelial (rod-like)
  • endothelial cells supported by an anastomosing ring of basement membrane and reticular fibers that encircle the sinusoid like the hoops of a barrel
214
Q

Splenic closed circulation

A

Terminal capillaries opens into the sinuses

215
Q

Splenic open circulation

A

Terminal capillaries open into red pulp

216
Q

Splenic immune functions

A
  • APCs to initiate immune response
  • Activation and proliferation of B and T lymphocytes
  • Production of Abs against antigen present in circulating blood (plasma cells)
  • Removal of macromolecular antigens from the blood (macrophages, neutrophils)
217
Q

Splenic Hemopoietic functions

A
  • removal and destruction of senescent, damaged, and abnl erythrocytes and platelets
  • Retrieval of iron from erythrocyte hemoglobin
  • Formation of erythrocytes during early fetal life
  • storage of blood, esp RBCs
218
Q

Yellow fever virus

A
  • arbovirus (+) ssRNA flavivirus
  • Africa and South America
  • urban cycle (humans and mosquitos)
  • sylvan cycle (monkeys and mosquitos)
  • capillary fragility and disruption of blood clotting system. Leads to localized bleeding and shock
219
Q

What does Yellow fever virus look like?

A
  • RNA virus, icosahedral nucleocapsid, enveloped, ss(+)RNA, class 4, flavivirus
220
Q

Yellow fever virus route of infection

A
  • Vector: Aedes mosquito
  • cytolytic and destroys the cells it infects
  • elevated: TGF-beta, TNF-alpha, IFN-gamma, IL-6
  • in liver: infiltrate of CD4+ and CD8+ and NK cells (councilman bodies)
221
Q

Clinical presentation of yellow fever virus

A

-severe systemic disease, flu-like symptoms, loss of liver, kidney, and heart function, hemorrhagic fever, shock. Mortality of infected is 50%

Lab tests: immunofluorescence, RT-PCR, ELISA, NO LIVER BIOPSY

Treatment: supportive care, vector control, vaccination

222
Q

Dengue Fever Virus

A
  • one of 4 related (+)ssRNA flavivirus
  • transmitted by Aedes mosquito
  • non-vector transmission through blood transfusion, organ transplantation, and needle stick injuries
  • BREAKBONE FEVER (severe muscle/joint pain)
  • Where? Southeast Asia and India. (also in South America, Central America, and Carribean/Mexico)
  • Mild flu-like infection but can occasionally become Dengue Hemorrhagic Fever (usually during second isotype exposure)
223
Q

What does Dengue Fever Virus look like?

A
  • RNA virus, icosahedral nucleocapsid, enveloped, ss(+) non-segmented genome (class IV), flavivirus
224
Q

Original Antigenic Sin

A
  • second serotype exposure is very dangerous because it is similar enough to the first that the body does not make new antibodies for it but the antibodies for the first serotype do not work quite right. The virus gets uptaken by dendritic cells but is not neutralized –> rapid replication and more virus. Very sick
225
Q

Clinical presentation of Dengue Fever

A
  • 25% experience a self-limiting febrile illness with mild to moderate hematological and biochemical abnormalities.
  • can also have: vascular leakage, coagulation abnormalities, and liver and CNS involvement

-Lab tests: immunofluorescence, RT-PCR, ELISA, direct isolation of the virus

  • Treatment: supportive care, vector control, and vaccination
226
Q

Chikungunya Virus

A
  • (+)ssRNA virus
  • transmitted by the Aedes albopictus mosquito
  • causes symptoms similar dengue fever in individuals with the complication of severe CHRONIC joint pain (years post infection)
  • severe cases can have neurological impairment and/or hemorrhagic fever
227
Q

What does Chikungunya Virus look like?

A
  • RNA virus, icosahedral nucleocapsid, enveloped, ss(+) non-segmented class 4, togaviridae, alphavirus
228
Q

Clinical presentation of Chikungunya Virus

A
  • causes symptoms similar dengue fever in individuals with the complication of severe CHRONIC joint pain (years post infection)
  • severe cases can have neurological impairment and/or hemorrhagic fever

Lab tests: immunofluorescence, RT-PCR, ELISA, direct isolation of the virus

Treatment: supportive care and vector control measures (no vaccine)

229
Q

Ebolavirus

A
  • RNA virus
  • transmitted by Fruit bat reservoirs- contact with fruit bat, monkeys, tissues/secretions, infected humans
  • Endemic in Africa (west and central)
  • 5 serotypes: ZEBOV, SEBOV, BEBOV, CIEBOV, REBOV
230
Q

What does Ebolavirus look like?

A

RNA virus, helical/pleomorphic nucleocapsid, enveloped, ss(-)RNA, non-segmented genome (class 5), filovirus

231
Q

Ebolavirus clinical presentation

A
  • necrosis in liver, spleen, lymph nodes, and lungs
  • hemorrhage causes edema and shock
  • mortality rate: 40%
  • no vaccination, supportive care
232
Q

Lassa Fever Virus

A

-(-)ssRNA arenavirus, primarily found in West Africa
- 20% of cases result in a severe hemorrhagic syndrome
- reservoir found in multimammate rat (rodent)
- virus spreads via aerosoled rat droppings, eating contaminated foods
- 95% spontaneous abortion rate in pregnant women

233
Q

What does Lassa Fever Virus look like?

A
  • RNA virus, helical nucleocapsid, enveloped, ss(-)RNA, segmented genome, class 5, arenavirus, mammarenavirus
234
Q

HPV, human papilloma virus

A

-STD, direct contact
- vaccine available
- wart disease
- effects E6 (increases turnover of p53 degradation) and E7 (promotes E2F to drive cell cycle and replication forcing cell proliferation) –> leads to malignancy

235
Q

What does HPV look like?

A
  • dsDNA, class 1, circular genome, icosahedral nucleocapsid, nonenveloped, papovaviridae
236
Q

What does KSHV look like?

A

dsDNA, group 1, linear genome, icosahedral nucleocapsid, enveloped, herpesvirus (gamma)

237
Q

Clinical presentation of KSHV

A
  • usually asymptomatic primary infection
  • Kaposi sarcoma derived from lymphatic and vascular endothelial cells
  • Dark purpuric rash on the skin
  • most common in immunocompromised pts (AIDs, HIV)
  • associated with primary effusion lymphoma and multicentric castleman’s disease (cancers of B cells)

Lab tests: tissue biopsy (spindle shaped tumor cells), PCR, Warthin-Starry silver staining

Treatment: ganciclovir (against lytic virus), IFN-alpha (leukocytic effects), no vaccine

238
Q

B cell development

A

Early Pro-B (DJ H chain recombo, start V-DJ recombo) –> Late Pro-B (V-DJ H chain recombo) –> Pre-B (H chain solidified, several rounds of cell division, VJ L chain recombo) –> Immature B (mIgM expression, negative selection, deletion, receptor editing, check auto-reactivity)

239
Q

B cell initial antigen receptor (BCR)

A
  • membrane bound IgM
  • the signaling chains CD79a, CD79b (aka Ig-alpha, Ig-beta)
240
Q

Pro-B stage

A
  • progenitor B cell, earliest stage of antigen-independent B cell development. Express CD43, CD19 (works with CD21, CD81), and RAG1/2. Also c-Kit which binds to stem cell factor expressed on bone marrow stromal cells- inducing proliferation)
  • 3 groups:
    1.) Early pro-B: TdT only
    2.) intermediate pro-B: TdT and CD45R
    3.) Late pro-B: CD45R and downregulate TdT and RAG 1/2
241
Q

CD45R

A
  • receptor for cell growth and differentiation
  • remains expressed on the surface throughout the remainder of B cell ontogeny
242
Q

Pre-B cells

A
  • divided into large mitotically active pre-B cells and small, non-dividing pre-B cells
  • Both large and small express IgM
  • Large has successfully rearranged the Ig heavy chain genes
  • large–> small, they rearrange their Ig light chain and upregulate RAG1/2 again
243
Q

The pre-B cell receptor:

A
  • IgM chain, 1 variable and 4 constant
  • Surrogate light chain (lambda5, Vpre-B)
244
Q

Immature B cell stage

A
  • Finals stage
  • successfully rearranged their light chain and express IgM
  • RAG1/2 downregulated
  • immature–> mature = express both IgM and IgD on the surface
  • exit bone marrow and migrate to periphery
  • TRANSITION PHASE
245
Q

Transition phases 1 and 2

A
  • Cross checking phases to ensure the B cell is not too autoreactive, and that it responds appropriately to antigen
246
Q

Negative selection of self reactive B cells

A
  • occurs in bone marrow (clonal deletion)
  • Limits development of antibody-mediated autoimmunity (apoptosis or editing)
  • some negative selection occurs in the periphery (not every self-reactive B cell is eliminated in the marrow because not every self-antigen is expressed there)
247
Q

What makes sure a B cell can respond to antigen

A
  • Tonic signaling from BAFF in the follicle
248
Q

Follicular (B-2) B cells

A
  • Secondary lymphoid organs
  • From precursors in bone marrow
  • highly diverse V region
  • Somatic hypermutation capable
  • Requires T cell help
  • High levels of IgG
  • possibly responds to carb antigens
  • Responds to protein antigens
  • Yes memory
  • Surface IgD on naive B cells
  • Has CD19/CD21, IgM, IgD, CD23
249
Q

WWhere does class switching occur?

A

in the germinal center

250
Q

What is the secondary signal for a B cell to become reactive with a Th cell?

A

CD40+CD40L (B+T, respectively)

  • causes: entry into the germinal center for class switching, IgM bearing memory cells from primary response, and Focus cells secreting IgM
251
Q

Primary immunodeficiency

A
  • immunodeficiency resulting from an inherited genetic defect in the immune system
  • Present at birth and creates help problems early on in life
252
Q

10 warning signs of primary immunodeficiency

A
  1. 4+ ear infections in one year
  2. 2+ sinus infections
  3. 2+ months of abx treatment with little effect
  4. 2+ pneumonias
  5. failure to gain weight or grow
  6. recurrent skin/organ abcesses
  7. persistent thrush in mouth or fungal infection in skin
  8. need for IV abx to clear infections
  9. 2+ deep-seated infections including septicemia
  10. a family hx of PI
253
Q

Leukocyte Adhesion Deficiency (LAD)

A
  • trouble with adhesion to the endothelial cells for WBC entry to tissue (all WBCs stay in the blood rather than getting to infection)
  • LFA-1 protein (integrin) is bad, usually from a defect in CD18
  • symptoms include: recurrent sickness, very high WBC count, IV abx can resolve symptoms
  • REBUCK SKIN WINDOW TEST IS DONE (disrupt skin and see what cells come over hours)
  • treatment: bone marrow transplant
254
Q

Chronic Granulomatous Disease (CGD)

A
  • failure of phagocytes to produce hydrogen peroxide and superoxide
  • ## is mostly problematic with catalase + organisms (staph aureus, aspergillus spp, Chromobacterium violaceum, pseudomonas, nocardia, etc)
255
Q

Proteins that make up the NADPH oxidase complex

A
  • p21
  • gp91(most common, X-linked)
  • p47
  • p67
256
Q

Diagnosing CGD

A

-DHR assay with PMA-activated neutrophils
- DHR: dihydrorhodamine: reduced by H2O2, will fluoresce
- Patient with CGD will have no right shift and no fluorescent effect
- gp91 x-linked males: 100% non-fxnal neutrophils, female carriers: 50% fxnal, 50% fluorescence

257
Q

Sample case of CGD

A
  • teenage male
  • severe shortness of breath, aspergillus fungal pneumonia
  • normal IgG, IgA, IgM, normal WBC response
  • failed DHR assay
  • end up with granulomas: giant cells with macrophage center that cannot rid of antigen, and t cell wall around it, engulfing it
258
Q

Chediak-Higashi Syndrome

A
  • a defect in intracellular vesicle trafficking
  • usually from gene LYST
  • trafficking issues occur everywhere in the body: granule vesicle problems, melanocyte melanosome–>keratinocyte problems, neuronal CNS trafficking problems
  • on histology you will see neutrophils with “stuck” granules
259
Q

Sample case of Chediak-Higashi syndrome

A
  • Newborn/young child
  • recurrent ear infections
  • cellulitis, lymph node infections
  • bruising easily/mild nosebleeds: platelet maturation is bad
  • albinism
  • sensitivity to bright light
  • NORMAL: WBC, serum Ig levels, and DHR test
  • GIANT CYTOPLASMIC GRANULES IN LEUKOCYTES
  • treatment: bone marrow transplant (will only fix immune problems, not other bodily trafficking problems)
260
Q

Mutation in CHS1/LYST leads to?

A
  • Chediak-Higashi syndrome
  • causes abnormal organeller protein trafficking, aberrant fusion of vesicles, and failure of transport
261
Q

Platelet dense bodies

A

vesicles that normally participate in platelet aggregation. Dysfunction of them is seen in Chediak-Higashi syndrome

262
Q

Heme is synthesized from:

A
  • glycine
  • succinyl CoA
  • Ferrous (2+) iron
263
Q

Disorders in heme synthesis cause

A
  • porphyrias
  • defects in heme breakdown causing jaundice
264
Q

Where are the major sites of heme biosynthesis?

A
  • Eyrthroid cells ( for O2 delivery in hemoglobin)
  • Liver (for redox enzymes like cyp 450)
265
Q

What steps of heme synthesis occur in the mitochondria?

A

First step: Succinyl CoA + glycine –delta-ALA synthase–> delta-ALA

Last two steps: Protoporphyrinogen IX –protopor. oxidase–> protoporphyrin IX –ferrochelatase and Fe2+–> heme

266
Q

What is the key regulated step in heme synthesis?

A

The production of delta-aminolevulinic acid by delta-aminolevulinic acid synthase

  • this enzyme is inhibited by negative feeback inhibition via Heme. This can be problematic when part of the pathway is blocked because there is no way to shut it off and it builds up intermediate products
267
Q

ALA synthase requires what?

A
  • pyridoxal phosphate (PLP, vitamin B6) as a cofactor
  • dietary deficiency = microcytic anemia due to impaired heme synthesis
268
Q

Where is Vitamin B6 (PLP) absorbed?

269
Q

ALAS1

A
  • catalyzes the decarboxylation of glycine and joins it to succinate, creating 5 carbon d-ALA
  • expressed ubiquitously and is responsible for HEPATIC heme synthesis.
  • on chromosome 3
  • negative feedback regulation by Heme at the level of mRNA stability and protein import to the mitochondria
270
Q

ALAS2

A
  • catalyzes the decarboxylation of glycine and joins it to succinate, creating 5 carbon d-ALA
  • expression is restricted to ERYTHROID LINEAGE
  • on X chromosome (X-linked disease)
  • positively regulated by iron and iron pool availability by regulating access of mRNA to ribosomes
271
Q

What can be treated with Hemin?

A
  • Acute intermittent porphyria (caused by a loss of porphobilinogen deaminase
  • hemin is a form of heme
272
Q

Iron response element

A
  • ALAS2: 5’ untranslated region of mRNA containing a stem loop
  • in the absence of iron, IRE-BP prevents the initiation of translation (aconitase)
  • iron binding displaces IRE-BP allowing for translation (aconitase)
  • therefore, heme is only made via ALAS2 when there is iron available
273
Q

X-linked sideroblastic anemia

A
  • inherited mutations that decrease ALAS2 activity
  • RBCs present as small (microcytic), and pale (hypochromic)
  • causes an increase in the uptake and accumulation of iron, promoting damage via ROS
274
Q

X-linked protoporphyria

A
  • ALAS2 mutations that lead to a GOF, or increase in activity
  • results in the accumulation of intermediates of heme synthesis
  • porphyrins accumulate in skin and cause photosensitivity when they are oxidized to free radicals by UV light
  • some patients develop liver disease
    -ALAS2 hyperactivity can look like ferrochelatase deficiency
275
Q

Porphyrias

A
  • defects in heme production characterized by the accumulation of porphyrinogens that cause neuronal, GI, and skin problems
276
Q

Accumulation of delta-aminolevulinic acid leads to:

A

neurological and GI symptoms (NO SKIN)

277
Q

Accumulation of Uroporphyinogen III, Coproporphyinogen III, or Protoporphyinogen IX leads to:

A

Neurological and GI symptoms ALONG WITH skin blistering with sun exposure

  • types of porphyria: ALA-dehydratase, Acute intermittent, Hereditary, and variegate
278
Q

What generally procedes an acute porphyria attack?

A
  • nutritional deficit
  • viral infection
  • drug exposure
279
Q

Non-acute porphyrias:

A
  • affect the liver, skin, and nervous system
  • types of porphyrias: Porphyria cutanea tarda, erythropoietic protoporphyria, congenital porphyria, and x-linked erythropoietic protoporphyria
280
Q

What is absent in porphyrias?

A
  • negative feedback on delta-ALA synthase by heme
  • intermediates accumulate rapidly
281
Q

Doss porphyria (delta-ALA dehydratase porphyria)

A

caused by an inherited mutation of the d-ALA dehydratase. Very rare inborne error of metabolism

  • characterized by: acute attacks of abdominal pain, and neuropathy
282
Q

Lead poisoning

A
  • Lead (Pb) acts as a non-competitive (active site binder- decreasing Vmax, not changing km) inhibitor of delta-ALA dehydratase
  • endogenous lead binding protein PbBP is protective against this
  • Characterized by: GI symtpoms, CNS symptoms
283
Q

Acute intermittent porphyria

A
  • most common porphyria
  • characterized by neuropsych disturbances and abdominal pain
  • caused by inherited defects in porphobilinogen deaminase
  • women 4x more affected than men (estrogen?)
  • dark urine, measured PBG deaminase activity in RBCs for diagnosis
284
Q

Drug for acute intermittent porphyria

A
  • GIVOSIRAN
  • liver targeted RNA that is converted to siRNA that directs the RISC nuclease to the ALAS1 (LIVER) mRNA (causes interruption, decrease in ALAS1 mRNA, delta-ALA, and porphobilinogen
285
Q

Porphyria cutanea tarda

A
  • most common NON-ACUTE porphyria
  • caused by deficient activity of uroporphyrinogen decarboxylase (UROD)
  • Type 1: sporadic
  • Type 2: familial, heterozygous for UROD mutation
  • more commonly seen in men because of alcohol use
286
Q

Type 1 porphyria cutanea tarda

A
  • over production of an inhibitor of UROD
  • production of inhibitor is induced by stresses such as HCV infection, drugs, ethanol, and oxidative stress
287
Q

Porphyria cutanea tarda symptoms

A
  • blistering of the skin after precipitating event (toxin exposure)
  • urine color is orange, and fluoresces under UV light due to the accumulation of uroporphyrin
  • New growth of hair on the face (hirsutism)
288
Q

Porphyria cutanea tarda treatment

A
  • blood letting
289
Q

What are required to convert heme to bilirubin?

A
  • Molecular oxygen
  • reduced NADPH
  • it is then transported to the liver with albumin
  • Biliverdin is GREEN (from O2 and heme oxygenase)
  • Bilirubin is YELLOW (from NAPDH and biliverdin reductase)
290
Q

What is a six carbon carboxylic acid sugar that is used to increase the solubility of excreted compounds (including bilirubin)

A

Glucuronate. In the liver, two glucuronates are added to bilirubin to form bilirubin diglucuronide (can be excreted in the bile ducts)

291
Q

Neonatal jaundice

A
  • occurs immediately after birth due to an increase in hemolysis and immature glucoronate conjugating system
292
Q

Hemolytic jaundice

A
  • occurs if there is excessive red blood cell destruction
293
Q

Hepatocellular jaundice

A
  • occurs if the liver is not functioning (can be from damage via alcohol overconsumption)
  • block of 2 UDP-GlcUA –> 2 UDP
294
Q

Obstructive jaundice

A
  • caused by a disturbance in bile drainage due to a gallstone or a tumor, etc
295
Q

What does elevated bilirubin indicate?

A
  • increased red cell breakdown or decreased conjugated capacity in the liver
  • Direct = conjugated (bilirubin diglucuronide)
  • indirect = unconjugated (Bilirubin)
296
Q

Hyperbilirubinemia

A
  • inherited deficiency in bilirubin-UDP-glucuronate transferase (UGT1A1)
  • Crigler & Najjar
297
Q

UGT1 gene

A
  • encodes a family of proteins with different substrate specificity. Their job is to add glucuronate to molecules to make them more excretable
  • UGT1A1 specifically adds a glucuronate to bilirubin. if this does not happen, Kernicterus occurs (treatment with phenobarbital to increase transcription from the A1 promoter)
298
Q

Kernicterus

A

Brain damage from a high level of bilirubin in a baby’s blood. It can cause athetoid cerebral palsy and hearing loss. Kernicterus also causes problems with vision and teeth and sometimes can cause intellectual disabilities.

299
Q

Aedes mosquito transmits:

A

• chikungunya
• dengue fever
• yellow fever
• Zika virus
• lymphatic filariasis

300
Q

Anopheles mosquito transmits:

A

• malaria (Plasmodium falciparum)
• lymphatic filariasis

301
Q

Culex mosquito transmits:

A

• Japanese encephalitis
• lymphatic filariasis
• west Nile virus

302
Q

E6 binds p53 and the cellular E6-AP enzyme

A

P 53 becomes ubiquitinated and targeted for degradation at the proteosome. P53 is targeted to ubiquitin ligase

303
Q

E7 binds Rb with high affinity

A

• high risk, HPV strains bind to RB with higher affinity
• blocks the ability of RB to hold E2F in check
• E2F allows for the expression of genes that allow for the progression through S phase

304
Q

LANA

A

Inactivates p53 and the RB tumor suppressor pathways

305
Q

K10

A

Viral interferon regulatory factor

306
Q

ORF22

A

Glycoprotein H (structural proteins/has been shown to have some anti-P 53 effects)

307
Q

vFLIP

A

Activates NFKB, promoting cell survival and allows for the production of anti-apoptotic genes

308
Q

v-cyclin

A

Induce entry into the S phase by counteracting the effects of p21 and p27

309
Q

CCR7 is a

A

Chemokine receptor, that facilitates trafficking when binding of an antigen pattern recognition receptor

310
Q

Red blood cell development (cell names)

A

Proerythroblast (blast cell) —> basophilic erythroblast —> polychromatic erythroblast —> orthochromatophilic erythroblast —> reticulocyte —> erythrocyte

• gradually get smaller
• orthochromo= condensed nucleus, extrusion

311
Q

Granulopoiesis cell development (names)

A

Blast cell —> promyelocyte (azurophilic, 2x size) —> myelocyte (multicolored granules) —> metamyelocyte (kidney bean nucleus) —> band cell (c shaped nucleus)

IHO (6 decks)

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