Immunology Lecture 6. Flashcards
What is the major site of T-cell development? which part specifically?
thymus - the site of TCR gene rearrangements
What do T-cells recognize?
Peptides derived from self or foreign antigens ONLY when bound to MHC
Which MHC does CD8 recognize?
MHCI
Which MHC does CD4 recognize?
MHCII
What is DiGeorge’s Syndrome?
lack of thymus/thymic function leading to human T cell immunodeficiency
What is the importance of “nude” mice?
loss of a transcription factor required for thymus EPITHELIAL differentiation
Where do hematopoietic precursors originate?
bone marrow
What happens in the cortex of the thymus?
positive selection and lineage commitment
What happens in the medulla of the thymus?
negative selection - thymocytes that survive leave via venues
What happens at the cortco-medullary junction of the thymus?
cells enter here via blood vessels
What happens to the thymus with age?
decline of function although you don’t become immune-deficient
How to T-cell precursors travel to the thymus from the bone marrow?
chemokine signaling molecules and sphingosine 1-phosphate receptors
Where do mature T cells go?
secondary lymphoid tissue where they wait to fight infection (spleen and lymph nodes)
CD34
stem-cell surface marker
Which chain on the thymocyte rearranges first?
betta chain
How does the cell know it’s made a successful Beta chain?
pre T-cell receptor (heterodimer to superdimer to pre T-cell receptor
How many attempts to achieve a productive rearrangement of the Beta chain locus?
2
When is the delta/gamma locus deleted?
when there is rearrangement of the alpha chain
What is Aire?
transcription factor - promiscuous transcription of genes that are not normally expressed in the thymus - ligands that are created to avoid autoimmune disease
What is the T cell repertoire?
sum of all the specificities of the mature T cells produced by the thymus
What is a regulatory T-cell?
suppressor T cell (esp of CD4 I think)
