Ti gamma A + delta TCS1+ T cells in human thymus. Analysis of the T cell receptor.

TcR1+ T cells in peripheral blood have been shown to express in an exclusive fashion either the Ti gamma A or the delta TCS1 epitope. Here, we characterize a subset of TcR1+ T cells in fresh thymus co-expressing the Ti gamma A and delta TCS1 epitopes. TcR1dim and TcR1bright clones can be distinguished. Biochemical and molecular studies on both types of clones generated from these thymocytes reveal a unique T cell receptor structure characterized by the use of a V gamma 9/C gamma 2-encoded 55-kDa gamma chain nondisulfide linked to a V delta 1-encoded delta chain.