T-Cell Receptor Alpha (TCRa)

As with B cells, the capability to recognize a given antigen is fixed in any particular clonal line of T cells. However, unlike B cells, T cells recognize antigen in combination with self major histocompatibility complex (MHC) determinants, i.e., the function is """MHC restricted.""" Many authors commented that """the chemical nature of the T-cell receptors has been elusive""". The development of monoclonal antibodies that recognize and precipitate clone-specific proteins on the surface of T cells has provided information on these receptor molecules. Studies in both mouse and man show that the TCR-delta gene (TCRD) lies within the TCRA locus, upstream from the estimated 50 to 100 J(alpha) segments and between V(alpha) and J(alpha). Whereas TCRD genes rearrange early in thymic ontogeny, TCRA genes rearrange much later.