Immunology I Flashcards
In blood, what suspends the free cells?
Plasma
What is Plasma minus the clotting factors?
Serum
What is the relative volume of Plasma/Cells?
Cells - 45% (this is called the hematocrit)
Plasma - 55%
What is the Leukocyte composition of the hematocrit?
1% (or so)
What does Plasma contain?
inorganic salts
Albumins
Globulins
Fibrinogen
What is the most abundant protein in Plasma that prevents edema?
Albumin
What is the function of Albumin?
they are Transport Proteins
Prevents edema
What Plasma protein serves to transport hormones, metals, and lipids, a subclass of which make up the antibodies?
Globulins
What subclass of globulins make up the circulating antibodies?
Gamma Globulins
What is the circulating clotting factor?
Fibrinogen
> Fibrin
What are the 3 main cell types of the hematocrit?
Erythrocytes
Thrombocytes
Leukocytes
What 2 categories of Leukocytes are there?
Granulocytes
Agranulocytes
What are the 3 Granulocytes?
Neutrophils
Eosinophils
Basophils
What are the 3 Agranulocytes?
Monocytes
Lymphocytes
Macrophage
What does the bone marrow do to form blood cells?
Hemopoiesis
Where does hematopoiesis occur early in fetal development?
Later in fetal development?
Yolk sac (mesenchyme)
Liver, spleen, lymph
If hematopoietic bone marrow is destroyed, where might hematopoiesis resume?
Liver and spleen
Where are lymphocytes made after puberty?
Lymphocytes
*after involution of thymus
What are the 2 major cell lineages from the Hematopoietic Stem Cell?
Lymphoid (B and T cells)
Erthromyeloid
RBCs, monocytes, neutrophils, eosinophils, basophils, and megakaryocytes
How many heme groups in hemoglobin?
4
What determines the Hemoglobin type?
the chain subtypes making up the tetramer
*HbA, HbA2, HbF
What type of chains make up HbA?
2 alpha
2 beta
What type of chains make up HbA2?
2 alpha
2 delta
What type of chains make up HbF?
2 alpha
2 gamma
What causes sickle cell anemia?
Gene defect in beta chain
*so abnormal HbA
What are 4 requirements of hemoglobin synthesis?
Iron
Vitamin B12 (cobalmin)
Vitamin B6 (pyroxidine)
Folic Acid
How long to RBC’s live and where are they broken down?
120 days
spleen
What happens to the RBC component after phagocytized in the spleen?
Released into circulation
reutilized (most)
excreted (bilirubin)
What is the destiny of the following upon RBC breakdown:
Iron?
Globin?
Heme?
Fe - re-used in bone marrow for new RBC’s
Globin - production AA’s
Heme - converted to Bilirubin
What 3 pathways can bilirubin take once in the intestine?
- re-used
- metabolized to urobilinogen - urine
- metabolized to stercobilinogen - feces
What is an RBC with residual RNA called?
Reticulocyte
- less than 1%
- *newly released into blood from marrow
What stain identifies reticulocytes?
Cresyl blue
What carries the recycled iron from RBC’s back to the bone marrow for re-use?
Ferritin
What type of Leukocytes have single or multi-lobed nuclei?
Granulocytes
*Poly’s and Seg’s
What is the most common type of leukocyte in the blood?
Neutrophils
*multi-lobed nuclei
What type of leukocyte makes up the majority of pus and is very active in cell inflammation?
Neutrophils
What 2 types of neutrophils are there?
What do they contain?
Specific granules - phagocytin and Lysozyme
Non-specific granules - peroxidases, hydrolases, acid phosphatase
How are neutrophils attracted to an infected area?
Chemotactically
What comprises 1-6% of circulating leukocytes, has a bi-lobed nucleus, and are attracted by substances released by basophils (mast cells)?
Eosinophils
What substance, when present, will cause eosinophils to have a direct destructive effect?
IgE
What is the least common leukocyte (less than 1%)?
Basophils
Basophils in circulation are equivalent to?
Mast cells in the connective tissue
What substance allows Basophils to migrate out of the vasculature during an inflammatory response?
Histamine
Heparin, the anticoagulant, is also involved but role is unclear
Another name for a monocyte?
Why is it agranular?
Macrophage
Nothing on the outside with specific lysing functions like neutro, eosino, baso-phils
T/F
Monocytes have pseudopodia?
True
*they are immature macrophages
T/F
Monocytes, macrophage, phagocytes, histiocytes, Kupffer cells, Dust cells, Microglial cells are all the same thing.
True
Where are the following located: Monocytes Macrophages Phagocytes/histiocytes Kupffer cells Dust cells Microglial cells
Bood Connective tissue Tissue Liver Lung Brain
What 2 cells participate in Phagocytosis?
neutrophils and macrophage
What is Opsonin?
To make tasty
bacteria is coated to enhance phagocytic efficiency
What cell has antigenic properties on its membrane receptors?
Lymphocytes
*also the “quarterback” of the immune system
Long-lived lymphocytes are thought to be…
Memory cells
What are the 2 main types of Lymphocyte?
T-cells (cell-mediated)
B-cells (humeral)
What are the 3 types of T-cells?
Helper (CD-4)
Cytotoxic (CD-8)
Memory Cells
What protein antibodies do B-cells secrete?
IgG IgA IgM IgE IgD
What are antibodies?
immuniglobulins composed of glycoproteins
*Y-shaped (mostly)
What antibody is pentagonal?
IgM
What are the inside (Fc), crystallized segments of the immunoglobulin (antibody)?
Heavy chains
What Antibody makes up 80% of immunoglobulins and crosses the Placenta?
IgG
What immunoglobulin crosses the placenta and is secreted in milk?
IgG
What antibody activates the compliment cascade and functions as an Opsonin?
IgG
What 2 antibodies are secreted in milk?
IgG
IgA
Which antibody is known as the secretory antibody?
tears, saliva, nasal cavity
IgA
Which antibody makes up 15% of immunoglobulins?
What is it shaped like
IgA
two Y’s
What 2 antibodies activate compliment?
IgG (need two?)
IgM
What antibody makes up 5-10% of immunoglobulins, activates compliment, and is first to form in immune response?
IgM
*also Pentameric
What antibody helps release histamine, attaches to Basophils (mast cells), and signals eosinophils to kill?
IgE
What antibody is found on B-cell surface and helps recognize antigens?
IgD
T/F
Both T-cells and B-cells have memory components.
True
What is located in the bone marrow and makes platelets?
Megakaryocytes
What do platelet granules contain?
Serotonin
vasoconstrictor
What clotting substances do platelets release when they degranulate?
Thromboplastin and Plasmin (a contractile protein)
What is the function of Thromboplastin?
Prothrombin > Thrombin
then Thrombin
Fibrinogen > Fibrin
Where are Prothrombin and Fibrinogen made?
Liver
What are the 3 types of immunity?
Cell-mediated (T-cells)
Humoral (antibody)
Complement
What is the difference between active and passive immunity?
Active: after contact with foreign antigens
(long memory)
Passive: Preformed antibodies in another host
(short duration)
What cells are seen in chronic inflammation?
Macrophages (monocytes)
*neutrophils too short-lived
What cells are important for the immuno-surveillance of viruses?
What receptors do they have?
Natural Killer cells
IgG receptors
(innate immune system)
How does degranulation occur in Mast Cells/Basophils?
IgE binds
releases Cytokines, which attract neutrophils and eosinophils
What cell acts as a bridge between innate and adaptive immunity and are Antigen Presenting Cells?
they are found in Langerhans in skin and interdigitating cells of lymph
Dendritic Cells
What do Dendritic Cells “present” to?
T-Helper cells (CD4)
What cells are central to allergic reactions and fight off parasitic infections?
Eosinophils
What are 3 major molecules that work with the innate immune system?
Complement
Acute phase proteins
Interferon
How many plasma proteins are involved in the Complement system?
What secretes these?
20
Hepatocytes/Monocytes
What are the 2 pathways of the Complement system?
Classical: Activated by IgG and IgM
(antibody dependent)
Alternate: substance or microorganism itself activates
What 3 main steps are there to Complement?
Recognition unit
Activation unit
Membrane Attack Unit
What comprises the Recognition unit in the Complement system?
C1 (trimolecular complex)
C1q, C1r, C1s
Where does the Recognition Unit bind?
C1q binds Fc portion of immunoglobulin
*the heavy chain
The Fc portion of the Recognition Unit must be either…
IgG or IgM
How many IgG Fc fragments does it take to activate C1q?
How many IgM?
2
1
What is the progression in the Activation Unit cascade?
C1q C1r C1s C4 C2 C3
When does the C4-C2 bimolecular complex become active?
When C1s allows them to fuse
What is the bimolecular complex of C4-C2 called?
C3 Convertase
What are the 2 components of the Complement System that act as an Anaphylactoxin?
C3a and C5a
What enzyme converts C3b into a complex with C4 and C2?
C3 Convertase
What is another name for the C4,C2,C3b complex?
C5 Convertase
What are the 2 roles of C3b?
Join with C4-C2 to make C5 Convertase
Land on target cell surface for immune adherence
What does the C5b fragment do?
Activates the MAC
Membrane Attack Unit
What does the fully assembled membrane attach unit consist of?
poly C9 with C5b,C6,C7,C8 attached
What is the roto-rootering component of the MAC?
C9
*drills into cell and lyses
What are the Acute Phase Reactants?
What is their function?
Cytokines that increase in response to inflammation
(IL-6/TNF-a)
opsonize, recruitment, etc.
What blocks the translation of Viral Proteins?
Interferons
What binds the heavy and light chains in immunoglobulins?
What is the stem of the Y composed of?
Disulfide bonds
Stem: only heavies
The arms of immunoglobulins are composed of…
Heavy and light chains
Fc and Fab
How long is the lag period in a primary response before we see antigens?
7-10 days
What are the first antibodies to appear and then go away in a primary response?
What next?
IgM
*followed by IgG or IgA
What is the lag period for antibodies to appear in a secondary response?
3-5 days
What are the differences in antibody expression between primary and secondary responses?
IgM comes on quicker in secondary
IgG is amplified in secondary and persists longer
What type of mechanism can’t be autoimmune?
Cell-Mediated Rxns
*all others can be (rely on antibodies)
What molecule receptor is involved in Anaphylaxis or immediate hypersensitivity rxn?
IgE cell bound receptors
(these bind IgE upon exposure to Antigen/Allergen)
*this is Type I
What causes hives?
Antigen-induced release of vasoactive mediators
What is Angioedema?
Similar to Urticaria (hives), but worse
What releases mediators in Anaphylaxis?
Mast cells or Basophils
What causes Cytotoxic Antibody Reactions?
Absorption of Antigen
(like blood transfusion)
IgG/IgM antibodies activate Complement
**Type II
What is the mechanism of Type III immune complex hypersensitivity reactions?
Circulating antigen/antibody immune complexes invade tissues and are then destroyed
(lupus, rheumatoid arthritis)
T/F
Type IV cell-mediated reactions involve antibodies.
False
What is the origin of stem cells for the lymphoid system?
mesenchyme derived yolk cell islands
then liver and spleen
What are the two Primary lymphoid organs?
Thymus
Bursa of Fabricus (avian)
Bursa Equivalent (mammalian)
*really there is only one
What does the Bursa Equivalent include?
GALT
(gut associated lymph tissue)
*includes tonsils, peyers patches
What forms Immunoglobulins?
Where did they come from?
Plasma Cells
B-Cells
What is the connective tissue framework in Lymphoid Tissue?
Reticular Fibers
Where are the T-cells usually found in lymphoid tissue?
B-Cells?
Diffuse T-Cells
Dense B-Cells
What do primary lymphoid organs lack?
What do they produce?
Reticular Fibers
T-cells
What is the Thymus composed of?
Trabeculae and Diffuse Tissue
What increases in the thymus with age?
Hassal’s Corpuscles
*implicated in T-cell death
T/F
Macrophages are present in the Thymus medulla.
True
What drives the proliferative activity of the Thymus in development?
Thymopoietin
The paracortical zone of a lymph node is comprised of…
T-cells
What makes up the cortex of a lymph node?
Nodules
B-cells
Where are macrophage found in Lymph nodes?
Sinuses of the medulla
What is the thick region of connective tissue at the efferent end of the lymph node?
Hilus
exit
Where are most invaders tagged in the lymph node?
Cortex
humoral
What phagocytizes antigens in the lymph?
Macrophage
Phagocytic Reticular Cells (aka Dendritic cells)
What do B-cells do in the cortical regions of lymph nodes in response to an antigen?
turn into Plasma cells and signal neutrophils, etc.
or activate Complement
What is the largest lymphoid organ of the body?
Spleen
- also blood filter
- *traps old blood cells
What makes up the red pulp (the majority) and the white pulp of the spleen?
Red - RBC’s
White - nodular lymphoid tissue (organized around arteries)
What does PALS stand for?
Where is it?
Periarteriolar Lymphoid Sheath
Spleen White pulp
What traps antigens in the spleen?
Marginal Zones
traffic cop
The diffuse lymphoid tissue (PALS) is populated with _____, while the nodules are populated with _____.
(both are White Pulp)
T-cells
B-cells
What is the function of Reticular cells in the spleen?
Antigen-Presentation
search and destroy antigens
When does Hemopoiesis occur in the Spleen?
Second Trimester
What are the 3 areas of the body that consist of diffuse and nodular lymphoid tissue?
Peyer’s Patches (ileum)
Tonsils
Appendix
What combats Parasites?
Eosinophils + IgE
What 4 cells participate in phagocytosis?
Neutrophils, Monocytes/Macrophage, Eosinophils
