Lymphocytes and their receptors Flashcards
What are immature T cells in the thymus called?
thymocytes
How is diversity in T cell response possible?
random rearrangement of gene segments that encode for TCRs (occurs in the thymus)
Where does selection of T cells occur?
thymus
Describe positive selection of T cells
T-cell must bind MHC to pass
elimination if it can’t
Commitment to CD4/8 lineage
96% fail this test
Describe negative selection of T cells
If TCR binds with too high an affinity for MHC present on an APC, the T cell dies by apoptosis
Why is negative selection important?
eliminates most T cells that will be self reactive
What are double negative/ positive T cells?
Early immature T cells lack both CD4/8
After expressing the alpha/beta TCR, immature T cells express both CD4/8
(mature T cells express only CD4 or CD8)
Where do B lymphocytes develop before birth?
yolk sac, fetal liver, bone marrow
Where do B lymphocytes develop after birth?
bone marrow, bursa of Fabricius (birds, maturation), peyer’s patches
