T cell development 1 Flashcards
Where is the B cell repertoire generated?
Bone marrow
Where do T cells develop?
The thymus
What do T and B cells differentiate from?
Hematopoietic stem cell precursors
What kind of lymphoid organs are the thymus and bone marrow?
Primary
Where do t cells migrate to after the thymus?
Lymph nodes
Where to t cells get activated against a specific antigen?
Lymph nodes
Difference between how intracellular vs extracellular pathogens are dealt with?
Intracellular–> cell is forced to undergo aopotiss by cytotoxic t cells
Extracellular–> antibodies
What do the developing t cells make contact with while in the thymus?
cortical epithelial cells
What are thymocytes?
Developing T cells
What do cortical epithelial cells do to thymocytes in the thymus?
Guide their development
What is the movement of t cells like during their development in the thymus?
They move throughout the lobule and move towards the medullary area of the thymus
What are macrophages there to do in the thymus?
Mop up dead cells
What are hassall’s corpuscle thought to be?
Regions of massive cell death-> where macrophages and dead cells accumulate
What is involution of the thymus?
Loss of thymic tissue over time
What is the lost thymic tissue replaced by?
Fatty tissue
When is the naive t cell population generated?
When a person is young
What is Di Georde syndrome?
Thymus fails to develop
Which two main components make up a TCR?
Alpha and Beta chains
What drives recombination in TCR genes?
RAG complexes
WHich bit of the beta chain codes for CDR3?
The VDJ junction
Where is the beta chain locus?
Chromosome 7
Where is the alpha chain locus?
chromosome 14
Different recombination in alpha and beta chains of TCRs?
Alpha = VJ recombination
Beta = VDJ recombination
What are the two classes of TCRs?
Alpha beta, and gamma delta
What are the %s of alpha beta t cells VS gamma delta t cells?
Alpha beta = 95%, gamma delta = 5%
Where is the gene locus for the delta subunit?
Within the alpha chain locus
Where is the gamma chain locus?
Chromosome 7
What does the uncommitted progenitor cell have on it when it arrives at the thymus?
Stem cell markers–> CD34 and CD44
What are CD34 and CD44?
Adhesion molecules
What happens when uncommitted progenitor cells enter the thymus?
They lose the stem cell markers and begin to express other adhesion molecules and signaling molecules
When do uncommitted progenitor cells commit to becoming t cells?
When they lose their stem cell markers and begin to express other adhesion molecules
When they start to rearrange their TCR genes
