Lymphocyte Activation and germinal center response

Question 1

what is the first step of lymphocyte activation

Answer 1

antigen binding to the antigen receptors on the B cells

Question 2

b cell activation starts with

Answer 2

polyvalent antigen cross linking the BCR

Question 3

what does Src-family kinase do

Answer 3

phosphorylates cytoplasmic tail of BCR

Question 4

what does syk do

Answer 4

binds phosphorylated ITAM causing activation of downstream signaling

Question 5

what are the steps of T cell help

Answer 5

• Tcell recognizes a peptide derived from antigen bound by the b cell receptor
• conjugated naive B and t cells exchange signals and initiate B-cell activation

Question 6

what are the steps of Antigen activation of T cells

Answer 6

peptide- MHC cross links with T cell receptor

Src family kinases phosphorylates cytoplasmic tail of TCR

Zeta chain assocatiated protein kinas 70 binds to the phosphorylated ITAM

Question 7

naive b and t cells occur

Answer 7

at the same time

Question 8

what are the steps of the concurrent initiation of B and T cell activation

Answer 8

• t cells are activated by MHC class 2 on dendritic cells
• b cells are activated by foreign antigens
• few days later activated B and T cells meet
• T cells help the B cells

Question 9

What are the two posibilities of the B cells

Answer 9

differentiation into antibody-producing plasma cell- making antigen specific IgM antibody

migrate to local primary follicle to initiate germinal center formation

Question 10

how many cell types are in germinal center?

Answer 10

3

Question 11

what are the 3 germinal center cell types

Answer 11

B cells ( centroblast and centrocytes)

T cells- CD4+ follicular helper

Follicular dendritic cells

Question 12

what is the process and result of the germinal center

Answer 12

centroblast divide

centrocytes test new BCR using antigen on FDC

The result is that B cells expressing higher affinity survive and turn into plasma cells

Question 13

germinal center centroblast induce

Answer 13

Activation-induced cytidine deaminase (AID) is an enzyme that plays a crucial role in the immune system, particularly in B cells, by initiating processes that lead to antibody diversity. AID achieves this by converting cytosine (C) in DNA to uracil (U), a process that introduces mutations or alterations in the genetic code

Question 14

germinal center centrocytes express

Answer 14

mutated BCR

Question 15

centroblast can also undergo

Answer 15

immunoglobulin class switching