CD8-CELL-MEDIATED SUPPRESSION OF HIV-1 LONG TERMINAL REPEAT-DRIVEN GENE-EXPRESSION IS NOT MODULATED BY THE CC CHEMOKINES RANTES, MACROPHAGEINFLAMMATORY PROTEIN (MIP)-1-ALPHA AND MIP-1-BETA( T)

Objective: To assess the role of RANTES, macrophage inflammatory prote in (MIP)-1 alpha and MIP-1 beta in modulation of HIV-1 long terminal r epeat (LTR)-mediated gene expression and determine whether these chemo kines share identity with CD8+ T- lymphocyte-derived HIV-1 LTR-suppres sive factors. Design: HIV-1 LTR-directed reporter gene expression is a model for transcription that is susceptible. to inhibition by factors produced by CD8+ lymphocytes of HIV-1-infected individuals. The effec t of recombinant chemokines on LTR-directed gene expression Was examin ed. The ability of chemokines found to be present in CD8 supernatants to suppress HIV-1 LTR-mediated gene expression was determined by antib ody inhibition assays. Methods: The concentrations of RANTES, MIP-1 al pha and MIP-1 beta in a panel of CD8+ T-lymphocyte-derived supernatant s were determined by enzyme-linked immunosorbent assay. Recombinant ch emokines were added to freshly transfected (pLTR-CAT and pSV40-tat), h uman jurkat T cells. Excessive polyclonal neutralizing antibodies to t hese chemokines were added to transfected Jurkat T cells cultured in t he presence of strongly inhibitory CD8+ T-cell-derived supernatants wi th known chemokine concentrations. Results: The concentrations of RANT ES, MIP-1 alpha and MIP-1 beta in a panel of CD8+ lymphocyte-derived s upernatants were found to correlate with their relative ability to sup press the LTR-mediated gene expression (r = 0.679, 0.764 and 0.48, res pectively). The addition of recombinant CC chemokines had no effect ov er a broad range of doses on HIV-1 LTR-mediated gene expression. The C D8-suppressive effect on HIV-1 LTR-driven gene expression was not abro gated by a combination of antibodies to RANTES, MIP-1 alpha and MIP-1 beta. Conclusions: RANTES, MIP-1 alpha and MIP-1 beta do not alter HIV -1 LTR-directed gene expression at doses up to 100 ng/ml. Although pre sent in varying concentrations in supernatants derived from CD8+ lymph ocytes from HIV-positive individuals, these chemokines are not respons ible for the powerful CD8-derived suppressive effect on HIV-1 LTR-medi ated gene expression observed in our system.