Transcripts of functionally rearranged gamma genes in primary T cells of adult immunocompetent mice

The T-cell specific, rearranging gamma-chain genes bear striking resemblance to T-cell receptor and immunoglobulin genes, but the role of gamma remains unknown. A central problem is to understand the conditions under which gamma RNA is expressed in cells. The transcription of gamma is abundant in T cells of fetal thymi, but is negligible in peripheral T cells of adults, suggesting that gamma is involved in development of the T-cell repertoire. However, gamma RNA was originally cloned from established lines of cytotoxic T cells (CTLs) derived from adult mice and this expression has been ascribed to non-physiological cell growth. Possibly consistent with this, most of the gamma RNA derives from genes rearranged abortively at the V gamma-J gamma junction of immunoglobulin genes, where V is the variable segment and J the joint segment. Here, we report the detailed analysis of gamma transcription in T cells of adult mice, and find that transcription may occur in T cells with a broad range of surface phenotypes; that it is predominantly of a single V gamma-C gamma unit (where C is the constant region); and that in cells freshly explanted from animals it can be of productively rearranged genes.