T cell development Flashcards
Epithelial component of the thymus
Develops bilaterally from the third pharyngeal pouch at 4 weeks gestation
When does the thymus split from the pharynx?
Between weeks 4 and 7
When is the thymus colonized with hematopoietic stem cells?
7th week
When does the thymus produce T cells?
12th week
When do T cells leave the thymus?
13th week
DiGeorge syndrome
Deletion in the 22nd chromosome; complete T cell deficiency and severe immunodeficiency
FOXN1 gene
On chromosome 17. Codes for a transcription factor necessary for maturation of T cells
Thymic epithelial cells
Produce cytokines important for growth and differentiation
Expresses notch receptors that are crucial for T cell lineage commitment
Expression of peripheral tissue antigens
Corticomedullary junction of the thymus
Where dendritic cells and macrophages reside for antigen presentation and phagocytosis of self-reactive T cells
What CD marker is present on the hematopoietic stem cells in the thymus?
CD34
Four developmental events in T cell maturation
T lineage commitment
Proliferation and differentiation
Selection
Maturation
Persistent Notch signaling
Commits T cells to the lineage; short signaling can cause NKT development OR T cell development
Notch ligands
DL-1 and DL-4
What happens once T cells commit to the lineage?
Express CD1, recombine delta, gamma, beta genes
What is required for recombination of T cells?
RAG-1 and RAG-2, as well as IL-7
