Chapter 7

Question 1

T cell precursors travel from the ______ to develop in the _______

Answer 1

bone marrow, thymus

Question 2

Mature T cells leave __________ and travel to _______

Answer 2

the thymus, secondary lymphoid tissues

Question 3

Thymocytes are:

Answer 3

developing T cells in the thymus > stroma cells

Question 4

What is central tolerance?

Answer 4

this occurs during lymphocyte development (only self-Ag in the thymus/ no foreign Ag)

Question 5

What is peripheral tolerance?

Answer 5

occurs after T lymphocytes leave the primary organs (back up system, lack of co stimulation by APCs)

Question 6

Process of early development of alpha beta T cells in the thymus

Answer 6

Progenitor cells> Proliferation> Double negative T cells commit to T lineage (CD4- CD8- T cells)> rearrange beta genes> [check point for pre-TCR]> proliferating double negative pre-T cells> Immature double positive cells (CD4+ CD8+ T cells)> rearrange alpha genes> [check point for TCR]> Mature double positive cells

Question 7

What does positive selection determine?

Answer 7

If a double positive thymocyte will become a CD4+ or a CD8+ T cell> selected by binding to either MHC I or MHC II (determines MHC restriction)

Question 8

What is negative selection?

Answer 8

Elimination of thymocytes bearing high affinity TCR for self-MHC molecules alone or self- antigen presented by self- MHC or self-Ag alone (self tolerance)

Question 9

What is clonal deletion?

Answer 9

Physical deletion done by macrophages and dendritic cells

Question 10

What happens when the mechanisms of negative selection of T cells fails?

Answer 10

Autoimmune diseases, production of self-reacting T cells