W4.4

Question 1

RAG-1 and 2

Answer 1

recombinase enzymes

Question 2

TdT

Answer 2

another enzyme that adds nucleotides at the splice sights -> increased diversity

Question 3

RSS

Answer 3

“Recombination Signal Sequences

- conserved DNA sequences beside each gene segment “

Question 4

Gene rearrangement

Answer 4

“Joining of segments occurs by somatic recombination

• each gene segment is flanked by RSS
• RAG1 and RAG2 recognize the conserved sequences; pull the RSS together and cleave the DNA “

Question 5

maturation steps of B cells

Answer 5

Stem cell -> Pro-lymphocyte -> Pre-lymphocyte -> immature clymphocyte -> Mature lymphocyte -> differentiated effector lymphocyte

Question 6

lymph node interaction

Answer 6

“(within the lymph node)

• Activation and migration of T and B lymphocytes
• T:B cell interaction
• Be cell differentiation: Ig secretion, isotype switching
• Germinal center reaction: affinity maturation, long-lived plasma cells, isotype switching, memory B cells “

Question 7

epitopes

Answer 7

“key portion of the immunogen
aka determinant site
- molecular shapes or configuration that are recognized by B or T cells “

Question 8

IgM and IgD

Answer 8

“M+D - expressed by Bcells right out of the bone, good at activating complement, help link innate and adaptive immunity
- complement is an ““effector”” molecule of the innate immune system “

Question 9

Class switching and cytokines

Answer 9

”- class switching (occurs with TD AG/ T cell help) is determined by the cytokines

• IFN-y induces IgM -> IgG switch
• IL-4 induces IgM -> IgE switch
• others induce IgM -> IgA “

Question 10

Mechanisms for bacterial immune evasion

Answer 10

“1 - the inhibition of phagocytosis and intracellular killing in the phagocyte
2 - inactivation of complement function
3 - cleavage of IgA
4 - intracellular growth (avoidance of antibody)
5 - change in bacterial antigenic appearance “

Question 11

Interferon functions

Answer 11

“1 - slow down synthesis
2 - cause degredation of mRNAs
3 - Enhance MHCI expression
4 - Activate NK cells “

Question 12

Mechanisms for viral immune evasion

Answer 12

"1 - latency 
2 - cell-to-cell infection
3 - decay complement 
4 - block interferon production/action
5 - decrease MHCI expression 
6 - decrease immune cell function 
7 - block inflammation "

Question 13

B cells can directly present antigen to a T cell in order to get T cell help (T/F)?

Question 14

once a B cell decided to switch to IgA, it can switch back to IgG (T/F)?

Question 15

Why do you think B cells require T cell help to become fully activated

Question 16

Somatic hypermutatation/affinity maturation