Unit 2

Question 1

When only 1 type of TCR or BCR is transcribed per cell.

Ex. 1 Heavy chain and light chain allele is transcribed/ B cell. 1 B and 1 a chain allele is transcribed / T cell.

Answer 1

Allelic Exclusion

Question 2

When does isotype switching occur? How does it occur?

Answer 2

When: After antigen is met, in the lymph node. The release of chemokines causes IgM or IgD to become IgG, IgA or IgE.
How: AID targets “switch regions” and removes them. This is regulated by cytokines

Question 3

When the constant region of antibody switches but not the variable region.

Answer 3

isotype switching

Question 4

Cytokines for isotype switching:

1. IL-4
2. TGF-B
3. IL-5
4. IFN-y

Answer 4

1. IgG1, IgE
2. IGA, IgG2b
3. IgA
4. IgG3, IgG2a

Question 5

When antigen binds to pAPC and activates a B or T cell, causing proliferation.

Answer 5

clonal selection

Question 6

many genes

Answer 6

polygeny

Question 7

many alleles of same gene

Answer 7

polymorphism

Question 8

exogeous pathway for MHC surface expression proteins

Answer 8

invariant chain, CLIP, HLA-DM

Question 9

endogenous pathway for MHC surface expression proteins

Answer 9

Immunoproteosome, TAP transporter, ER

Question 10

How does cross presentation work?

Answer 10

Antigens engulfed by a protein gets placed into pathway for MHC Class I.

Question 11

T Cell Development: Process

Answer 11

1. T cell precursor in the thymus 2. B forms and proliferates (somatic recombination). 3. good B are selected (surrogate a chain is added and goes to the surface. If it binds well to CD3, B works) 4. a is formed. 5. DP (CD8 and CD4 forms) 6. Can either become a T reg, death by neglect, or bind to cortical endo cells with MHC class I or II. 7. SP cells go to medulla. 8. If not bind to MTECS, go to tissues for activation. If bind, either anergy, apoptosis, or receptor editing.

Question 12

B Cell Development: Process

Answer 12

1. pre-pro B cell in bone marrow. 2. Heavy chain is recombined. Surrogate L chain binds and goes to cell surface and proliferates. 3. Light chain forms. 4. If binds to self antigens in bone marrow–> apoptosis or receptor editing. 4. Goes to spleen T1 (produces a lot of IgM). 5. T2 reaches follice and starts producing igD. 6. B-2 cells produce both and goes to activation.

Question 13

When B cells are self reactive in bone marrow

Answer 13

Central Tolerance

Question 14

When self reactive B cells are killed

Answer 14

Clonal Deletion

Question 15

T Cell activation (helper)

Answer 15

1. TCR binds to antigen on MHC class II. 2 Costimulatory molecules on pAPCS bind. 3. cytokines.

Question 16

Cytokine signalling for T Cell Differentation

1. IL-2, TGF-B
2. IL-1, IL-6, IL-23, TGF-B
3. IL-4
4. IL-6, IL-21
5. IL-12, IFN-y, IL-18

Answer 16

1. T cell produces IL-10, TGF-B–> T reg
2. IL-17A,IL-17 B, IL-22–>Th17 cell (protects fungal and bacterial, inflammation)
3. IL-4, IL-5, IL-13–>Th2 cell (allergy and anti-helminth)
4. IL-4, IL-21–>Tfh(helps B cells in follicles and germinal center in spleen)
5. IFN-y, TNF–>Th1(enhances cytotoxic T cell activation, APC activity, intracellular pathogen)

Question 17

What consists of central SMAC

Answer 17

TCR/CD3, CD4/CD8, CD28 on T Cell–CD80/86 on APC

Question 18

What consists of peripheral SMAC

Answer 18

LFA-1 (T) –ICAM-1 (APC), CD2(T)–IFA-3(APC)

Question 19

Which type of cells are present class I and classII MHC

Answer 19

class I is present in all nucleated cells, class II in pAPCs.

Question 20

Gene for MHC

Answer 20

II (DP, DQ,DR), III (C4, C2, BF), I (BCA)

Question 21

What is the name of the transcription factor that picks random genomes and adds them to medulla epithelial cells in thymus?

Answer 21

AIRE

Question 22

Costimulators can be negative or positive

Answer 22

Immunomodulation