T Cell and APC Signals 1, 2, and 3!

For Immunology Chapter 11 Day 1

1. “Signal 1” occurs when a TCR recognizes antigen within an MHC molecule on an antigen presenting cell. Then, transcription of IL-2 and CD25 occur.  What is the significance of the upregulation in these two genes?
2. What molecular interactions would you expect to find in cSMACs and pSMACs? What purpose do these interactions serve?
3. We have been saying that “signal 2” occurs when CD28 molecules on T cells interact with CD80/CD86 molecules on APCs. Describe the outcomes of these other types of signal 2 interactions.
   1. ICOS and ICOS-L
   2. CTLA-4 and CD80/86
   3. PD-1 and PD-L1/L2
4. What professional APCs would you most likely find in secondary lymphoid organs? Where in the SLO would they be and why would they be there?
5. Do superantigens simulate signal 1, 2, or 3? How?
6. Mosmann and Coffman studied clonal CD4+ T cells to look for heterogeneity in a polyclonal T cell culture. They found that the 50 clones that they studied fell into two groups based on cytokine production.  What did they call these two groups?  What appeared to be the general purpose for each group?