Diversity and structure of human T-cell receptor beta-chain variable region genes.

Abstract

The nucleotide sequences of 27 T-cell receptor .beta. cDNA clones isolated from a human peripheral lymphocyte library were determined and compared to five additional published sequences. These cDNA clones represent 22 distinct T-cell receptor .beta.-chain variable region (V.beta.) gene segment sequences, which fall into 15 different V.beta. gene subfamilies, each containing six or fewer members. From this analysis, we estimate that the repertoire of expressed human V.beta. genes is < 59, apparently much smaller than the immunoglobulin heavy chain and light chain variable region (VH and VL) repertoires. Variability plots comparing these human V.beta. regions with each other and with published mouse V.beta. regions provide evidence for only four hypervariable regions homologous to those seen in comparisons of immunoglobulin V regions. Somatic hypermutation appears to be used infrequently, if at all, in these V.beta. genes.