How do T cells recognize their targets? The acquired immune system consists of two major cell types, T and B cells, which recognize specific antigens. They differentiate from hematopoietic precursors and from each other in the bone marrow, with T cells migrating off to mature in the thymus (hence the name). The T cell is endowed with receptors (TCRs) of unique specificity, created by somatic DNA rearrangement and random chain pairing. In the thymus, T cells are selected for their ability to recognize MHC (major histocompatibility complex) class I or II molecules; those with too strong an affinity for self-derived peptides are deleted from the repertoire.
Where do T cells do their work? From the thymus, T cells migrate to secondary lymphoid organs such as the spleen, lymph nodes, Peyer's patches, and tonsils. There they are "primed" by antigen-presenting cells (APCs), which display the appropriate peptide-MHC complex.
What are the ...
