Frequent occurrence of in vivo clonal expansion of CD4- CD8- T cells bearing T cell receptor alpha beta chains in adult humans

Kusunoki Y, Hirai Y, Hayashi T, Kyoizumi S, Takahashi K, Morishita Y, Kodama Y, Akiyama M
Eur J Immunol 23:2735-9, 1993

Summary

We have previously reported 2 cases of healthy men showing in vivo monoclonal expansion of mature CD4^– CD8^– alpha-beta T cells. In the present study, an additional 3 adults were found to exhibit such an expansion, among a total 464 adult donors studied. These 5 individuals were otherwise physiologically normal, with no history of severe illness and autoimmune disease at the time of examination. To investigate the mechanisms of the clonal expansion, further characterization of the clonal cells was attempted. No apparent preference for usage of the T cell receptor beta chain variable region was observed in the clonal T cells. These clonal T cells showed lectin-dependent or redirected antibody-dependent cell-mediated cytotoxicities, whereas they could not lyse autologous lymphoblastoid cell lines. Failure of Fas antigen expression was not observed for any of these clones. These results suggest that clonal expansion of CD4^– CD8^– alpha-beta T cells frequently occurs in the periphery without any T cell abnormalities.