exam 1

Question 1

Describe Eosinophils

Answer 1

Bilobed nucleus, granulocyte, phagocytic
High affinity for IgE, low affinity for IgG
Key role in fighting parasitic infections
small role in allergic rxns
Important in the pathogenesis of asthma and other chronic inflammatory diseases

Question 2

Describe Basophils

Answer 2

Granulocyte
Cross linking with Fce receptors with IgE and its antigen -> degranulation
Minor role in Allergic reactions
granules contain histamine and vasodilators

Question 3

Mast cells

Answer 3

Found in CT tissues and skin, granulocyte
High affinity surface for IgE
*play a major role in allergic responses
Cross linking with Fce leads to degranulation
Granules contain histamine and vasodilators

Question 4

Layering

Answer 4

2 types: innate and adaptive

Question 5

Redundancy

Answer 5

A single pathogen can be fought by the immune system multiple ways (e.g. different phagocytes, different Abs)

Question 6

The 2 immune responses

Answer 6

First: recognition that a pathogen is present (cell-surface receptors, serum proteins)
Second: recruitment of effector mechanisms to kill and eliminate the pathogen (e.g. Abs and complement)

Question 7

Innate immunity

Answer 7

Prevents establishment of a pathogen in most cases
non-specific (mucus, skin), always present at basal levels (always on)
elements you are born with, physical/anatomical barriers (skin, blinking)
-Macrophage, neutrophil, enzymes, NK cell, fever, inflammation, complement, cytokines

Question 8

Adaptive immunity

Answer 8

Acquired and specific to an antigen
-slower to develop activated B&T cells increase in number (clonal expansion)
-Provides memory
2 types: Humoral (Ab think missiles) and Cell mediated ( think hand-to hand combat T cells)

Question 9

Cell mediated immunity

Answer 9

adaptive, protects against INTRAcellular pathogens (virus)
T cells: CD8+ CD4+ Th1 CTLs
direct killing by T cells

Question 10

Humoral immunity

Answer 10

adaptive, involves production of Abs
Protects against EXTRAcellular pathogens (bacterial)
B cells
T cells: CD4+ Th2 
Complement

Question 11

Cellular components of Adaptive immunity

Answer 11

Naïve cells (yet to encounter their antigen/unprimed) before activation
Effector cells: carry out immune function
Memory cells: circulate and await next encounter with the antigen( can quickly become effector cells
Granulocytes: Basophils, eosinophils, mast cells

Question 12

Antigen presenting cells (APCs)

Answer 12

adaptive immunity
Dendritic cells (#1), macrophages, B cells
All have MHC 1 and MHC 2
-Engulf pathogens, break them down into smaller pieces and present them to T cells

Question 13

Non-cellular components of the adaptive immunity

Answer 13

Antibodies- produced by activated B cells
Cytokines- produced by activated immune cells (T cells, macrophages, NK cells)
Complement - proteins circulating in the blood stream

Question 14

Papain

Answer 14

3 pieces
2 Fab (fraction antigen binding)
1 Fc (fraction crystallizable)
Hinge present before Ab is treated with papain ( flexible region only present in CH3 domains IgG, IgA, IgD)

Question 15

Fab

Answer 15

2 of them only when treated with Papain
-This portion can bind antigen
Contains VL, CL and VH, CH1

Question 16

Fc

Answer 16

Only made when treated with Papain
1 piece includes most of the hinge region(below), CH2, CH3 (&CH4 if it’s present)
-opsonization occurs when the Fab portion binds antigen while the Fc portion is bound by Fc receptors on immune cell that phagocytose the antigen. (need Fab to opsonize)
-Delivers the Ab to specific anatomical sights

Question 17

F(ab’)2

Answer 17

Only 1 piece made when treated with pepsin (think pepsi 1)

- single piece made up of both Fab regions and the hinge (Fc is not generated)

Question 18

Hinge region

Answer 18

found between CH1 and CH2
-allows the Fab arms to open and close to accommodate binding 2 epitopes
Only present in Abs with CH3 domains (IgA, IgG, IgD)

Question 19

J chain

Answer 19

Only present with polymeric IgA, IgM

• only 1 J chain per molecule
• J chain is required for polymerization and interacts with Poly-ig or pIg receptor to transport (transcytosis) of antibodies from basal side to the lumen

Question 20

CH4

Answer 20

4 ME
CH4 domains are only on IgM and IgE
-No hinge region

Question 21

Describe Neutrophils

Answer 21

1 phagocyte - releases defensins to punch holes in the membrane

Makes cytokines: IL-1,IL-6,IL-8,TNF-alpha
Most predominant Granulocyte, Polymorphonuclear cells
lives less than/equal to 2 days
50 billion at any given time

Question 22

Hypervariable regions

Answer 22

Hypervariable region = complementarity-determining regions (CDR1,CDR2, CDR3) There are 12 CDRs per molecule: 3 from each L-chain and 3 from each H-chain (IgG has 12 CDRs, IgM has 60 CDRs, dimeric IgA has 12 CDRs)
8-11 stretch of AA that are extremely varied.
These AA make contact and form bonds with the epitope, and they are the exact region that determines antigen specificity

Question 23

Framework regions

Answer 23

The remaining 80 AA of the V region between the CDRs show less variability.
There are 4 FRs in each V region (FR1, FR2, FR3, FR4)

Question 24

Isotypes of Abs

Answer 24

Determines the Class (IgG, IgA, IgM, IgE, IgD)

e.g of an isotype IgG1k, IgM(lambda)

Question 25

what determines Ab function and what are the 4 functions

Answer 25

``` CH region determines function and anatomical location Functions: Opsonize Neutralize Complement activation ADCC ```

Question 26

IgM

Answer 26

``` Monomeric BCR, made exclusively as a PENTAmer, has CH4 domain Most predominant isotype made in response to T-independent antigens (need 2nd signal to class switch) -most efficient isotype for activating the classical complement pathway -Gengival cervicular fluid is a major source of Igm in saliva ONLY isotype made by a FETUS and infants until 4-6 months ```

Question 27

IgG

Answer 27

Four subclasses in humans (in this order IgG1, IgG3, IgG2, IgG4) hinge region is the structural characteristic to distinguish subclasses -Most predominant in serum( but not most abundant) -Half live is the largest 23 days Only isotype to cross placenta and is present in titers for 6 months IgG1, IgG3, IgG2 activate the classical complement pathway -Can bind Fc receptors to increase opsonization (IgG1 is the best opsonin) -Can participate in ADCC (antibody-dependent cell-mediated cytotoxicity) when bound by Fc receptors on NK cell ***Production of IgG begins when an infant is 4-6 months old

Question 28

IgA

Answer 28

2 subclasses (IgA1, IgA2) IgA1 is most predominant in serum (5:1 ratio) ratio is 1:1 in mucosal secretions -most abundant of all Abs in quantity made, 2nd in serum after IgG Most predominant found in secretions (tears, saliva, mucus, breast milk) IgA is in both serum (s) and Secretions (S)

Question 29

IgA1

Answer 29

Most monomeric IgA is found in serum (s) | -is generally directed against protein epitopes

Question 30

IgA2

Answer 30

Polymeric IgA, dimeric, found in secretions (SIgA), 24 CDRs Is generally directed against polysaccharide epitopes SIgA is secreted by salivary glands into the oral cavity -helps protect from proteolytic cleavage