Chapter 4 - Antigen Recognition in the Adaptive Immune System

Question 1

what are the forms of antigens that B cell receptors recognize? T cell receptors?

Answer 1

B cell: macromolecules such as proteins polysaccharides, lipids, nucleic acids and small chemicals. conformational and linear epitopes
T cell: mainly peptides displayed by MHC molecules on APCs. linear epitopes

Question 2

what is antigen recognition in B cell receptors mediated by? T cell?

Answer 2

• B cell: variable regions of heavy and light chains of membrane Ig
• T cell: variable regions of alpha and beta chains of the TCR

Question 3

what are the B cell receptors for antigens

Answer 3

• secreted IgG
• membrane IgM

Question 4

what are CDRs

Answer 4

3 variable antigen binding loops

Question 5

what is the function of IgA

Answer 5

mucosal immunity

Question 6

what is the function of IgD

Answer 6

naive B cell antigen receptor

Question 7

what is the function of IgE

Answer 7

defense against helminthic parasites, immediate hypersensitivity

Question 8

what is the function of IgG

Answer 8

opsonization, complement activation, antibody dependent cell mediated cytotoxicity, neonatal immunity, feedback inhibition of B cells

Question 9

what is the function of IgM

Answer 9

Naive B cell antigen receptor, complement activation

Question 10

describe the generation of hybridomas and monoclonal antibodies

Answer 10

• isolate spleen cells from mouse immunized with antigen X
• spleen B cells and mutant immortal myeloma line fuse
• culture in selection medium
• only fused cells grow
• isolate clones derived from single hybridoma cells
• screen supernatants of each clone for anti-X antibody and expand positive clones

Question 11

what is the immunoglobulin made up of

Answer 11

three CDRs in VH and three CDRs in VL

Question 12

what is the TCR made up of

Answer 12

three CDRs in Valpha and three CDRs in Vbeta

Question 13

what are the steps in the maturation of lymphocytes

Answer 13

• common lymphoid progenitor
• Pro- B/T cells
• Pre B/T cells
• immature B/T cells
  -mature B/T cells

Question 14

describe the process of recombination and expression of immunoglobulin genes

Answer 14

• first somatic recombination D-J joining in two B cell clones
• second somatic recombination V-DJ joining
• transcription
• RNA processing (splicing)
• translation

Question 15

what are the types of diversity in antigen receptors

Answer 15

combinatorial diversity and junctional diversity

Question 16

enzyme mediating recombination is a _____plus ____ to heal the double strand breaks created in the process

Answer 16

lymphoid specific recombinase; repair enzymes

Question 17

what is the result of weak recognition of Class II MHC + peptide

Answer 17

positive selection

Question 18

what is the result of weak recognition of Class I MHC and peptide

Answer 18

positive selection

Question 19

what is the result of no recognition of MHC + peptide

Answer 19

failure of positive selection

Question 20

what is the result of strong recognition of either class I or class II MHC and peptide

Answer 20

negative selection