For Immunology Chapter 9 Day 2
- After jumping through the hoops necessary to make functional α and β chains of their TCRs, ~95% of CD4+CD8+ (DP) thymocytes die from what? Because of this fact, why are quotes necessary when someone says thymocytes “learn” or are “educated” in the thymus?
- What stages of T-cell development (DN1, DN2, DN3, DN4, DP, CD4 SP, or CD8 SP) would be affected in mice with the following genetic modifications? Justify your answers.
- Mice that do not express MHC class II
- Mice that do not express AIRE.
- Mice that do not express the TCRα chain.
- You stain thymocytes with PE-conjugated anti-CD3 and FITC-conjugated anti-TCRβ. Most cells stain with both. However, you find a proportion of cells that stain with neither antibody. You also find a small population that stain with anti-CD3, but not with anti-TCRβ. What thymocyte populations might each of these populations represent?
- The overview figure for this chapter (9-1) shows that “Positive and negative selection” occurs in the thymic cortex and that “Negative selection” occurs in the thymic medulla. Compare and contrast the two forms of negative selection. (Hint: In which negative selection step does “AIRE” play a role?)
- Describe the experiments where Hogquist and colleagues made use of 1) the fetal thymic organ culture (FTOC) system and 2) mice deficient in TAP-1. From these experiments, what is the estimated difference in binding affinity between cells that are negatively vs. positively selected?