Ch9 T cell development

Question 1

What is the significance of Notch protein.

Answer 1

Key in determining T cell lineage, can be grown in bone marrow stem cells using Notch

Question 2

List the steps from the beginning to end of T cell maturation. Key terms: progenitor T cell, Thymus, thymocyte, proliferation, differentiation, positive and negative selection, “BROWSING”. Death by neglect. TCR alpha-beta or gamma delta

Answer 2

Proginator T cell migrate from Bone marrow to thymus, at this time they lack all markers making them T cells such as RAG, CD4, CD8. Once in the thymus, thymocytes proliferate and differentiate and begin to undergo selection by BROWSING, Once the TCR is formed (most likely alpha beta). Browsing: if the TCR does not bind to MHC at all, it is death by neglect. If it binds to self peptide and MHC or self MHC too strongly it is eliminated by negative selection. If the TCR bind just right and correctly to MHC, it “passes” and survives via positive selection. The mature T cell will leave the thymus.

Question 3

What are 4 effects Treg cells have and how does a T cell become a Treg cell?

Answer 3

deplete local area of cytokines, produce inhibiting cytokines, inhibit APC activity, directly kill T cells.
A CD4+ T cell can become a T reg cell by expression of Foxp3 trascription factor