Regulation of the mature human T cell receptor gamma repertoire by biased V-J gene rearrangement.

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Abstract
To delineate how gene rearrangement influences the expressed human gamma delta T cell repertoire, we generated T cell receptor gamma (TCR gamma) V domain-specific cDNA libraries from the peripheral lymphocytes of eight donors and sequenced a total of 232 TCR gamma gene transcripts. The libraries consisted of both in-frame and out-of-frame rearranged TCR gamma genes. The in-frame TCR gamma gene transcripts were used to determine the diversity of functional T cells, whereas the out-of-frame transcripts, primarily derived from alpha beta T cells, were used to assess the frequencies of TCR V gamma-J gamma rearrangements in progenitor T lymphocytes. The results showed that both sets of transcripts exhibited strikingly restricted V gamma-J gamma combinations. Only 11 of 40 potential V gamma-J gamma rearrangements were common ( > or = 3% of total). The pattern of gene usage in the functional and nonfunctional transcripts was similar and did not differ markedly among donors. The only exception was the predominance of V gamma 9-JP in potentially functional transcripts from seven of eight individuals. These results show that V gamma-J gamma rearrangement is nonrandom and suggest that the diversity of TCR gamma genes in the functional gamma delta T cell repertoire partly depends upon preferentially rearranged V gamma-J gamma gene combinations. However, the expansion of V gamma 9/V gamma 2 T cells in adult peripheral blood can only be explained by antigenic selection of relatively rare V gamma 9-JP recombinants.