CD3-gamma, -delta, -epsilon, -zeta, T-cell receptor-alpha and -beta transcripts are independently regulated during thymocyte ontogeny and T-cell activation.

CD3 proteins transduce signals delivered from the T-cell receptor (TcR) for antigen. The genes that encode the individual CD3 subunits are asynchronously regulated in tumour cell lines in vitro. In this report, we examined the expression of individual CD3 and TcR genes during normal murine thymocyte ontogeny in vivo. We show that CD3-gamma, -delta, -epsilon, and zeta transcripts are all expressed on Day 14 post-coitum (p.c.), along with IL-2R alpha and Thy-1 mRNA, and prior to the expression of functional TcR-alpha, -beta, CD4 and CD8 transcripts. Individual CD3 subunits display unique patterns of increased gene expression as ontogeny proceeds. Unique regulation of these T-cell transcripts is also observed in splenic cells activated with the T-cell mitogen concanavalin A (Con A). CD3-delta, -zeta, TcR-alpha and -beta mRNA expression increases, whilst CD3-gamma and -epsilon mRNA levels decrease after mitogenic activation. The potential implications of this regulation on the composition and expression of the TcR/CD3 complex during T-cell ontogeny and activation is discussed.