Single Positive - has either CD4 or CD8
CD2 and CD5 - perform adhesion and signaling. They are present during double negative stage
Thymocytes rearrange which 3 genes at the same time? - Beta, gamma, and delta
pTalpha - surrogate alpha chain. signals cell to halt gamma, delta, Beta chains, gene
...
Notch-1 - The signal for survival. It drives the cell on the T-cell path — signals to open up T-cell
rearrangement.
Signaling rearrangement keeps T-cel on T-cell pathway
Where does Maturation and Positive Selection occur? - Cortex of the thymus
Can negative selection also take place in the Cortex? - Yes, negative selection can take place in the
cortex at the same time as positive selection
,Where does negative selection take place? - medulla of thymus
Where are mature thymocytes located? - Medulla
Where are immature thymocytes located? - Cortex
What special cells are in the Medulla - Dendritic cells, macrophages, and medullary epithelial cells
What special cells are in the cortex? - Cortical epithelial cells and macrophages
Where can you find AIRE? - in the medullary epithelial cells
AIRE - Autoimmune regulator
made by medullary epithelial cells
Creates a couple hundred peripheral peptides that can be used to test T-cells for negative selection
DiGeorge's syndrome - deletion in chromosome 22 in which thymus fails to develop and T-cells
are absent
Positive Selection - makes sure that your T-Cell recognizes one of your MHC.
If it does not, then apoptosis
Negative Selection - Makes sure it does not recognize your peptide:MHC too strongly
Does gamma: delta T-cells have to go through positive selection? - No
, What does turning off RAG 1&2 do to your gene rearrangement? - Preserve the current
rearrangement
Primary Lymphoid Tissue - bone marrow and thymus
Hassall's corpuscles - macrophages in both cortex and medulla remove the many thymocytes that
fail to mature properly
Involution of the Thymus - Progressively shrinks, fat gradually claiming areas once packed with
thymocytes
-reduces production of new T-cells
Double negative - No CD4 and CD8
Double Positive - CD4 and CD8 are present
How many rearrangements can successfully make a Beta chain? - up to 4 attempts
d:k light chain can have a minimum of how many rearrangements? - 4 minimum attempts
alpha chain allows many successive rearrangements with a minimum of - 2 attempts
What is the first checkpoint in T-cell maturation? - Pre-TCR
Checking beta chain is a productive rearrangement
What is the second checkpoint in T-cell maturation? - TCR
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