Expression of killer inhibitory receptors on cytotoxic cells from HIV-1-infected individuals

Dysfunction of cytotoxic activity of T and natural killer (NK) lymphocytes is a main immunological feature in patients with AIDS, but its basis are no t well understood. It has been recently described that T and NK cell-mediat ed cytotoxicity can be regulated by HLA killer inhibitory receptors (KIR). In this work, we have determined on cytotoxic T cells and NK cells from HIV -1-infected individuals the expression of the following KIR molecules: p58, p70, and ILT2 (immunoglobulin-like family KIR) as well as CD94 and NKG2A ( C-lectin-type family KIR). With some exceptions, no significant changes wer e found on the expression of immunoglobulin-like KIR in either CD8(+) or CD 56(+) cells. Interestingly, the percentages of CD8(+) and CD56(+) cells exp ressing CD94 were significantly increased in these individuals. We also sho w that, in vitro, IL-10 up-regulates CD94 expression on CD8(+) and CD56(+) cells obtained from normal individuals, suggesting that the augmented expre ssion observed in HIV-infected individuals could be related to the high lev els of IL-10 previously described in HIV-1-infected individuals.