Chapter 3 ( Lymphocyte Development And Selection )

Question 1

Type of antigens recognized by TCR ?

Answer 1

Small antigenic peptides

Question 2

Signal transduction complex and co-receptor of B lymphocytes ?

Answer 2

Ig-alpha
Ig-beta

CD19,20,81

Question 3

CD21 is the receptor for ?

Answer 3

EBV

Question 4

CD81 is the receptor for ?

Answer 4

Hepatitis C

Plasmodium vivax

Question 5

Signal transduction complex of T cell ?

Answer 5

CD3

Question 6

Mechanism for generating receptor diversity ?

Answer 6

1- existence in genome of multiple V,D,J segments
2- VDJ recombination
3- N-nucleotide addition by Tdt
4- combinatorial association of heavy and light chains
5- somatic hypermutation ( in B cells only after antigen stimulation )

Question 7

Omenn syndrome mode of inheritance ? Molecular defect ? Symptoms ?

Answer 7

AR

Missense mutation in RAG genes leads to RAG enzyme with partial activity

Symptoms :
Lack of B cells
Marked decrease in predominantly Th2
Early onset failure to thrive , red rash , diarrhea and severe immunodeficiency

Question 8

SCID mode of inheritance ? Molecular defect ? Symptoms ?

Answer 8

AR

Nonsense mutations in RAG genes leads to No RAG enzyme activity

Symptoms :
Total lack of B and T cells
Total defect in humoral and cell-mediated immunity

Question 9

Anergic B cells express high level of what ?

Answer 9

IgD on their surface rendering them inactive

Question 10

MHC genes location ?

Answer 10

On short arm of chromosome 6

Question 11

MHC I gene products ?

Answer 11

HLA-A
HLA-B
HLA-C

Question 12

MHC II gene products ?

Answer 12

HLA-DM
HLA-DP
HLA-DQ
HLA-DR

Question 13

Structure of MHC l ?

Answer 13

The molecules A , B , and C consists of :
1- alpha heavy chains with 3 extracellular domains and intracytoplasmic carboxy terminus
2- A second light chain ( Beta 2 microglobulin )
3- a groove between the first two domains of the heavy alpha chain which accommodates the antigen ( small peptides ) to present it to TCR

Question 14

Function of Beta 2 microglobulin ?

Answer 14

Peptide loading and transport of class l antigen to the cell surface

Question 15

Professional antigen presenting cells ?

Answer 15

Macrophages
Dendritic cells
B lymphocytes

Question 16

Structure of MHC ll ?

Answer 16

2 chains structure of similar length called alpha and beta each one of them have 2 extracellular domains and 1 intracytoplasmic domain
A groove that will accommodate peptides to be presented to TCR at the N-terminal end of both chains

Question 17

Regulatory T cells ( Tregs ) express what on their surface ? Secret what ? Function ?

Answer 17

CD 4
CD 25
FoxP3

IL-10 and TGF-beta which inhibit inflammation

Critical in the prevention of autoimmunity by inhibition of self-reactive Th1 cells in the periphery