T-CELL RECEPTOR V-BETA REPERTOIRE IN HIV-INFECTED INDIVIDUALS - LACK OF EVIDENCE FOR SELECTIVE V-BETA DELETION

The gradual decline of CD4+ T lymphocytes in HIV-infected individuals culminates in the lethal immunosuppression of AIDS. The mechanism of C D4+ T cell loss is currently unknown, but has recently been suggested to occur as a result of an HIV-encoded superantigen which facilitates a selective deletion of T cells expressing specific Vbeta genes. To ve rify and extend such observations, peripheral blood leucocytes (PBL) f rom 15 HIV+ individuals, 10 of which had very low CD4 T cell counts ( < 200/mm3), were analysed for T cell receptor (TCR) Vbeta gene express ion. In contrast to a recent study, the results presented here fail to provide evidence that selective loss of Vbeta-bearing T cells occurs in HIV+ individuals. Furthermore, when PBL from HIV+ individuals were stimulated with Staphylococcal enterotoxin B (SEB), T cells expressing Vbeta subfamilies known to engage this superantigen were expanded, in dicating that such cells were not deleted and were responsive to stimu lation by a bacterial superantigen. Collectively, these data suggest t hat CD4 loss in HIV patients does not occur in a Vbeta-selective, supe rantigen-mediated fashion.