Upregulation of T cell receptor gamma chain transcription by interleukin-2.

Signals involved in TcR gene rearrangement and expression are poorly understood. The ability of interleukin 2 to control TcR gamma gene expression was examined. Precursor thymocytes grown in the presence of IL-1 and Con A develop to CD3+ T cells that express either the TcR alpha/beta or gamma/delta complex on the cell surface (1). We show here that a major subpopulation of these cells are CD4-/CD8-, gamma/delta cells expressing only low levels of TcR gamma transcripts, compared to TcR delta mRnA or to TcR gamma mRNA of gamma/delta cells grown from precursor thymocytes with IL-2 and Con A. The cells cultured with IL-1 and lectin then strongly reacted to IL-2 by upregulating the steady-state level of TcR gamma mRNA. Our findings indicate that IL-2 upregulates TcR gamma transcription by transcriptional regulatory effects in this in vitro system.