{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"The T cell receptor or TCR is a protein found on the surface of T lymphocytes that is responsible for recognizing antigens bound to major histocompatibility complex (MHC) molecules. The TCR is a heterodimer composed of two different protein chains. In 95% of T cells, TCR consists of an alpha (α) and beta (β) chain, whereas in 5% of T cells, TCR consists of gamma and delta (γ/δ) chains. T cell receptor delta locus (TRD), also known as TCRD, is encoded by the TRD gene in humans. Deletions and mutations of the TRG (T cell receptor gamma locus) and TRD gene have been implicated in a variety of cancers. Specifically, γδ T cells may contribute to the immune response against several tumor types (lymphoma, myeloma, breast, colon, lung, ovary, and others). They act directly through mediation of cytotoxic activity and indirectly through the regulation of other cell types responsible for the anti-tumor response. The presence of γδ T cells in the tumor microenvironment has been associated with poor prognosis in some cancers."}]}]}