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Flashcards in T cell development Deck (18):
1

central tolerance

tolerance to self antigens that is established in lymphocytes developing in central or primary lymphoid organs

mainly achieved by clonal deletion

2

clonal deletion

elimination of immature lymphocytes when they bind to self antigens which produce tolerance of self.

3

chemokine

chemoattractant cytokine that stimulates the migration and activation of cells

4

DiGeorge's syndrome

failure to develop thymic epithelium. parathyroid glands are absent and there are anomalies in the large blood vessels

5

negative selection

during intrathymic development, thymocytes that recognize self are deleted from the repertoire

6

positive selection

only those developing T cells whose receptors can recognize antigens presented by self MHC molecules can mature in the thymus.

7

signal transduction

general process by which cells perceive changes in their environment.

8

thymic anlage

produces chemotactic factors that attract T cell progenitors

9

CD4-CD8-

double negative, least mature T cells, considerable cell division, undergoes gene rearrangment for TCR beta/gamma/delta, least plentiful, is located in the outer cortex

10

CD4+CD8+

double positive, TCR alpha rearrangement, most plentiful, located in the inner cortex

11

CD4+CD8- or CD4-CD8+

single positive, most are mature cells with high levels of CD3 and TCR beta. There are twice as much CD4 than CD8 in the medulla. Most single positive cells leave the thymus.

12

Single Positive with low CD3 and TCR beta

immature (ISP), transitional cells that are on the way from DN to DP.

13

First Checkpoint (Beta selection)

asseses whether TCR beta chain is functionally rearranged

mediated by pre-TCR, involves RAG, CD3 epsilon, TCR beta, pT alpha.

if you knock out RAG genes, can't make TCR, blocked at double negative stage

14

Second Checkpoint (positive/negative selection)

assesses whether TCR alpha is functionally rearranged, whether TCR is self MHC restricted, whether the TCR is auto-reactive.

mediated by mature alpha beta TCR. involves TCR alpha, MHC Class 2, beta 2 microglobulin, bare lymphocyte syndrome

knock out TCR alpha, blocked at DP stage, unable to make SP.

15

cells that promote positive selection

cortical epithelial cells

16

cell types that can induce negative selection

thymic DC, cortical epithelial cells, medullary epithelial cells

17

cells that cannot induce negative selection

thymic macrophages

18

Aire transcription factor

AIRE is a transcription factor expressed in the medulla of the thymus and controls the mechanism that prevents the immune system from attacking the body itself