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Immunology > Lecture 1-cells, Organs > Flashcards

Lecture 1-cells, Organs Flashcards

1
Q

What is immunity?

A

Recognition of and reaction to foreign agents

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2
Q

What are foreign agents?

A

Pathogens
Host cells that infected, necrotic, neoplastic
Allergens, chemicals
Mismatched tissue or blood.
Foreign agents are composed of antigens which can be: proteins, carbohydrates (strong antigens-make good vaccines), nuclei acids ne lipids (weak antigens)

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3
Q

What are the mechanisms used by leukocytes to destroy antigens?

A

Phagocytosis-Ingestion and digestion of antigen particles
Cytotoxicity- induction of apoptosis in tumors, tissue grafts and infected host cells
Synthesis of soluble factors- antibodies, complement, cytokines, aid in the elimination of antigens

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4
Q

What are the branches of immunity?

A

Innate Vs adaptative

Humoral VS cell mediated

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5
Q

What are the characteristics of innate immunity?

A 
Natural, native
Present and functional at birth
Rapid response (within minutes)
Discriminate between self and non self
Low specificity
No memory
Not enhanced by vaccination
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6
Q

What are the components of innate immunity?

A

Natural barriers (skin, mucus, ph extremes, sneezing)
Phagocytes, granulocytes, natural killer cells
Soluble mediators(complement, CRP, cytokines)
Pattern recognition receptors
Normal flora microbes

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7
Q

What are the characteristics of adaptive immunity?

A 
Acquired
Induced by antigen contact 
Slow response (take days)
Able to discriminate between self and non self
Highly specific
Memory
Enhanced by vaccination
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8
Q

What are the components of the adaptive immunity?

A

B lymphocytes, plasma cells
Antibodies/immunoglobulins
T lymphocytes

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9
Q

What is the mechanism of clinal selection?

A

Antigen is specific to one type of T or B cells
Contact of antigen with matched receptor cells causes proliferation of that cell
From one cell we have thousand of cells for that antigen
proliferation is followed by differentiation
Differentiation gives rise to cells secreting specific antibody for the antigen and memory cells
Memory cells reside in spleen and lymph nodes and can be used for further production of antibodies

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10
Q

What are the characteristics of humoral immunity?

A

Most effective against extracellular bacteria
Antibody (immunoglobulin) is the most common
But includes:
Complement-pathogen lysis
C-reactive protein (CRP)-activates complement, general marker of infection and inflammation

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11
Q

What are the characteristics of the cell mediated immunity (CMI)?

A

Effective against intracellular and extracellular pathogens, tumors, damaged host cells
Can be :
Phagocytes-monocytes, neutrophils, eosinophils, macrophages
Granulocytes- neutrophils, eosinophils, mast cells, basophils
Cytotoxic cells-NK cells, Tc cells–> apoptosis of targets

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12
Q

What is opsonization?

A

Humoral immunity and CMI work together
Opsonins are ( antibody, complement and CRP) are substances that coat the capsule of bacteria to facilitate phagocytosis
Opsonins neutralize anti phagocytic property of bacterial capsules

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13
Q

What is hematopoiesis?

A

Formation of red blood cells, leukocytes and platelets from multipotent stem cells
Formation of 2 major lineages
Myeloid
Lymphoid

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14
Q

What is the mechanism of formation of the lymphoid lineage cells?

A

Stem cell under the influence of IL-7 gives the common lymphoid progenitor (CLP)
CLP gives B lymphocytes, natural killer cells and in the thymus T lymphocytes
T lymphocytes can further differentiate into T helper cells and cytotoxic T cells

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15
Q

What is the mechanism of the formation of the myeloid lineage cells?

A

Stem cell differentiates into common myeloid progenitor (CMP)
CMP+erythropoietin gives erythropoietin CFU which differentiates into erythrocytes
CMP+IL-3, GM-CSF+ thrombopoietin(IL-11) gives megakaryocyte which gives platelets
CMP+IL-3, GM-CSF gives basophil CFU which differentiates into basophils
CMP+IL-3, GM-CSF+Il-5 gives eosinophil CFU which differentiates into eosinophils
CMP+IL-3+GM-CSF gives granulocyte-monocyte CFU
G-M/CFU+G-CSF (filgrastim) gives neutrophils
G-M/CFU +M-CSF gives monocytes

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16
Q

What a re some clinical uses of CSF and ILs?

A

Erythropoietin (Epoetin, EPO)- Reverse anemia, restore RBCs especially in renal failure
G-CSF (Filgrastim)- Recovery of bone marrow, restore PMNs
GM-CSF (Sargramostim)-Recovery of bone marrow, restore PMNs, monocytes and macrophages
Interleukin 11 (oprelvekin)-Reverce thrombocytopenia, restore platelets
Thrombopoietin (TPO)- Reverse thrombocytopenia, restore platelets

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17
Q

What are the markers and cell function of B lymphocytes?

A

CD markers: CD19, CD 20, CD21

Function: antibody secretion-humoral immunity

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18
Q

What is the marker common to all T lymphocytes?

A

CD 3

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19
Q

What are the markers and function of T helper cells?

A

CD3, CD4

Function: cytokines secretion

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20
Q

What are the markers and function of the T regulatory cells (Treg)?

A

CD3, CD4, CD 25

Function: prevent autoimmunity

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21
Q

What are the markers and function of cytotoxic T cells (Tc)?

A

CD3, CD8

Functions: Killing of infected or neoplastic cells, rejection of grafts

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22
Q

What a re the markers and functions of natural killer cells (NK)?

A

CD16, CD56

Functions: killing of infected or neoplastic cells, rejection of grafts

23
Q

What are the markers and functions of Natural Killer T cells (NKT)?

A

CD3, CD16, CD56 plus TCR and NK1.1

Function: prevent infection through gut

24
Q

What are the functions of the innate lymphoid cells (ILCs)?

A

Protection and inflammation of mucosa

25
Q

What are the characteristic of B lymphocytes?

A

Develop in bone marrow (humans), bursa (birds)
In infant they are produced in the bone marrow and liver
Function in humoral immunity
Produce antibodies (immunoglobulins/Ig)-toxin and microbe neutralization, opsonization and complement activation
Differentiate into plasma cells or memory B cells

26
Q

What are the characteristics of T lymphocytes?

A

Mature in thymus
All express TCR (specificity) and CD3 (signal transduction)
Differentiate into T helper cells, cytotoxic T cells and T regulatory

27
Q

What are the subdivisions of the T helper cellls?

A

TH1- promote cell mediated immunity
TH2-promote antibody synthesis by B cells (allergies)
TH17- promote clearance of extracellular bacteria and fungi, contribute to asthma and autoimmunity

28
Q

What are the characteristics of the Natural Killer cells?

A

Only cells off the lymphoid lineage that are from the innate immunity
Kill infected and neoplastic host cells
Collaborates with IgG during antibody dependent cel mediated cytotoxicity (ADCC)

29
Q

What are the characteristics of the mononuclear phagocytes?

A

Horseshoe-shaped nucleus
Circulating monocytes
Dendritic cells
Tissue fixed macrophages-line for years and comprise the reticuloendothelial system (RES)
RES is a filtering system for antigen removal from blood and lymph
Function in phagocytosis, antigen processing and presentation

30
Q

What are the types of mononuclear phagocytes?

A 
Kupffer cells in the liver
Alveolar macrophages in the lung
Splenic macrophages
Peritoneal macrophages
Microglial cells in the brain
Osteoclasts in the bone
Mesangial cells in the kidneys
Synovial A cells in the joints
31
Q

What are the steps of phagocytosis?

A

Chemotaxis(migration) of macrophage toward bacterial f-met-leu-phe
Adherence to microbe aided by opsonins
Extension of pseudopodium to form phagosome
Fusion of phagosome and lysosomes to form phagolysosome
Digestion-lysozyme( also found in tears, saliva, sweat genitourinary secretions) breaks down peptidoglycan in bacterial cell wall
Respiratory burst-ROS damage protein, DNA

32
Q

What are the steps of antigen processing and presentation?

A

Processing-destruction of antigen in phagolysosome
Presentation
antigen fragments paired up with MHC
Complex transported to macrophage surface and presented to T cell
T cell can’t see antigen unless presented along with MHC by APC

33
Q

What are the characteristics of the dendritic cells?

A 
Related to macrophages
Found under epithelia,in most organs
Langerhans cells in skin
Most efficient APC
Activate naive T cells
34
Q

What are the characteristics of the polymorphomuclear granulocytes ?

A

Short-lived
Bilobes or multilobed nucleus
Granules contain enzymes (lysozyme, others) and lactoferrin harmful to microbes
Produce ROS

35
Q

What are the components of the polymorphonuclear granulocytes?

A

Neutrophils- killed extracellular bacteria-Phagocytosis and inflammation (60-%)-receptors for IgG
Eosinophils-killed worms (helminths)- participate in immediate hypersensitivity reactions -Receptors for IgE
Basophils-Killed worms-Participate in immediate hypersensitivity reactions , good source of histamine- receptors for IgE
Mast cells-killed worms-participate in immediate hypersensitivity reactions, major source of histamine-receptors for IgE, tissue fixed, long lived

36
Q

What are the characteristics of megakaryocytic lineage?

A 
Megakaryocyte:
Large cell with lobulated nucleus
Gives rise to platelets/thrombocytes
Platelet:
Anucleate
Blood cl;outing and inflammation
37
Q

What is the normal count of WBC?

A

Total WBC should be between 4800-10,800 per microliters

38
Q

What are the characteristics of lymphoid organs and tissues?

A

Sites of lymphocyte maturation, differentiation, proliferation
Can be 2 types
Primary
Secondary

39
Q

What are the general characteristics of primary lymphoid organs?

A

Antigen receptors are first expressed here
consist of :
Bone marrow-where B cells begin surface immunoglobin expression
Thymus where T cell begins TCR expression

40
Q

What are the general characteristics of secondary lymphoid organs?

A

B and T cells respond to antigens here (clonal selection)
consist of:
Lymph nodes
Spleen-site of most antibodies production
MALT-adenoids, tonsils, Peyer’s patches, appendix, BALT

41
Q

What are the characteristics of bone marrow?

A

Site of hematopoiesis
Stem cells express CD34 and Stem Cells antigen 1 (SCA-1) used to harvest stem cells for immmune reconstitution
Stromae cells secrete cytokines that drive differentiation
Site of B cell maturation

42
Q

What are the steps in B cells maturation?

A 
Stem cell gives Pro B
Pro B gives Pre B
Pre B gives immature B
Immature B gives Mature B
Mature B differentiate into memory B cell or plasma cell
43
Q

What are the characteristics of Thymus?

A

Site of T cell maturation
Develops from 3rd and 4th pharyngeal pouches
Reaches max size at puberty
Atrophies with age

44
Q

What is DiGeorge syndrome?

A

Defect associated with thymus
Little/no thymus
Few/no T cells–>heightened susceptibility to viruses and cancer
22q11.2 microdeletion
Deficient parathyroids–>hypocalcemic tetany
Deformed ears, facial anomalies
Heart and kidney defects

45
Q

What are the steps in T cell development in the thymus?

A 
In the subscapsular region:
Double negative thymocytes
Neither CD4 or CD8 present
In the cortex:
Double positive thymocytes
Both CD4 and CD8 present
In the medulla:
Single positive T cells-Either CD4 or CD8 present, both TCR and CD3 present
Hassall's corpuscles-Function in dendritic cell and /or Treg maturation
46
Q

What are the characteristics of lymph nodes?

A

Respond to antigens entering through skin or subcutaneous tissues
Encapsulated clusters
Function :
in survey of lymph by macrophages
storage/activation of B and T lymphocytes
Antibody production
Constant circulation of lymphocytes between lymph nodes, tissues, lymph and blood

47
Q

What is the structure of the lymph node?

A

Cortex (B cells)
Paracortex (T cells)
Medulla

48
Q

What is the characteristic of the cortex?

A

Primary follicles- naive B cells
Secondary follicles-germinal centers contain dividing B cells
No/few secondary follicles in patients with B cell deficiencies

49
Q

What are the characteristics of paracortex?

A

Poorly developed in DiGeorge syndrome
HEVs facilitate entry of lymphocytes from blood into node
Enlarged during cellular immune responses

50
Q

What are the characteristics of Medulla?

A

Cords contain lymphocytes and plasma cells

Sinuses contain macrophages, drain into efferent lymphatics

51
Q

What are the characteristics of the spleen?

A 
Responds to blood-borne antigens
Major site of antibody synthesis 
Asplenic persons are susceptible to encapsulated bacteria like (strep pneumonia, H.influenza, Neisseria meningitis)
Red pulp-hemocathereis
White pulp- Lymphocytes
52
Q

What are the characteristics of splenic white pulp?

A

PALS-T cells surround a central arteriole

B cells rich follicles-primary and secondary germinal centers

53
Q

What are the characteristics of MALT?

A 
Respond to antigens entering through mucosal surfaces
B cells produce secretory IgA
50% of bodys lymphoid tissue
GALT(Gut)
BALT(Bronchus)
GU-ALT(Genito-urinary)
Peyers patches of small intestine
Tonsils, adenoids, appendix, mesenteric lymph nodes etc.
54
Q

What are the M cells?

A

Unique to Peyers patches

Epithelial cells that mediate transcyotosis of antigens from lumen to subepithelial T cells

Immunology (8 decks)

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