Two types of T cell antigen receptors (TCRs) are now known, the α/β, and the γ/δ heterodimer, which are expressed at the cell surface in association with the CD3 molecular complex. TCR-γ can occur in either disulphide-linked or non-disulphide-linked forms. The γ/δ T-cell receptor is present on a minor subset of T lymphocytes in peripheral blood, thymus, spleen, and lymph node. In man and Mouse, only a small part of the T lymphocytes of the peripheral blood (<5%) is γ/δ. γ/δ T lymphocytes may complement α/β T cells in terms of antigenic specificities, functional capabilities, or sites of action within the body.
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