Repertoire of the human T cell gamma genes: high frequency of nonfunctional transcripts in thymus and mature T cells

To further understand the structural diversity and function of the human T cell‐specific γ gene, 20 human γ gene cDNA from both thymocyte and peripheral blood T lymphocyte libraries were sequenced and analyzed. Evidence of greater germ‐line multiplicity and more extensive use of junctional flexibility, N‐region diversity and perhaps D_γ gene segment incorporation was observed. In spite of the larger γ gene repertoire found in humans compared to mice, the potential of the human γ gene message to encode a functional product appears to be severely limited. In addition to the extremely low levels of γ gene expression observed, each of the 20 γ gene cDNA exhibit some form of deleterious mutation defect. This is in sharp contrast to the finding that human and mouse T cell antigen receptor α and β messages isolated from various sources have functional coding potential in most cases. Thus, the role of the human T cell γ gene becomes even more uncertain than before.