Linking Innate and Adaptive Immunity 7

Question 1

what do signal 1 and 2 lead to?

Answer 1

IL-2 and IL-2 receptor expression

T cell proliferation

Question 2

what type of cytokine response system is IL-2? why?

Answer 2

T cells produce the cytokine AND its receptors

Question 3

what happens when IL-2 binds IL-2R?

Answer 3

causes activation and induces a very strong PROLIFERATION SIGNAL

Question 4

what is produced from the proliferation signal?

Answer 4

memory and effector clonal cell populations

Question 5

what part of IL-2R is expressed upon signal 1 and 2?

Answer 5

IL-2R alpha

Question 6

what is another name for IL-2R alpha?

Answer 6

CD25

Question 7

when is IL-2R alpha expressed? when is it not expressed?

Answer 7

expressed upon T cell activation

not expressed in naive T cells (baseline)

Question 8

how do signal 1 and signal 2 cause increased IL-2 and IL-2R alpha expression?

Answer 8

signal 1 and 2 initiate downstream signaling cascade to cause activation of transcription factors to activate genes for IL-2 and IL-2R alpha

Question 9

do IL-2 and IL-2R alpha have the same gene? what does this mean?

Answer 9

NO!

this means signal 1 and 2 activate 2 diff genes thru downstream signaling

Question 10

what are the 3 chains of IL-2R? when are they expressed?

Answer 10

1. IL-2R beta –> constitutively expressed
2. IL-2R gamma –> constitutively expressed
3. IL-2R alpha –> only when signal 1+2

Question 11

why does IL-2 not bind IL-2R beta and gamma?

Answer 11

has very low affinity –> no proliferation can occur

Question 12

how does the affinity of IL-2 to IL-2R change when IL-2R alpha is expressed?

Answer 12

high affinity –> proliferation can occur

Question 13

a T cell mutant does not respond to activation signals. You discover there are low levels of IL-2 mRNA, high levels of ITAM phosphorylation, low levels of TFs in nucleus. What is the most logical next step in order to identify the cause of the defect?

A) Measure CD3 surface expression
B) Measure TF binding to target genes
C) Measure Zap-70 kinase activity
D) Measure co-receptor expression
E) Measure TCR expression

Answer 13

C) Measure Zap-70 kinase activity

everything upstream of ITAM phosphorylation is fine, so CD3, co-receptor, and TCR are fine

would not be able to measure TFs binding to genes bc we already know they didn’t make it to the nucleus

something went wrong btwn ITAM phosphorylation and transport of TFs into nucleus –> Zap-70 is btwn these steps