ENHANCEMENT OF NK CELL-MEDIATED ANTIBODY-DEPENDENT LYSIS OF RECOMBINANT GP120-COATED CD4 CELLS BY COMPLEMENT

The contribution of complement to NK cell lysis of CD4 cells expressin g recombinant gp120 (rgp120) was investigated. Peripheral blood mononu clear cells were used as effector cells in a Cr release assay against purified CD4 target cells that had been coated with rgp 120. Assays in cluded human immunodeficiency virus (HIV) antibodies and a complement source alone and in combination to determine their importance in media ting cytotoxicity. NK cells were confirmed to be the effector cells in the lysis of rgp120-coated CD4 targets. Anti-HIV was crucial for lysi s and cytotoxicity was enhanced by C3 deposition on targets. However, a prozone effect was observed, with reduced IgG binding, C3 deposition , and NK cell lysis at serum concentrations >10 mu g IgG/mL. The susce ptibility of these CD4-gp 120-antibody-C3 complexes to NK cell lysis m ay contribute to progressive depletion of CD4 cells in HIV infection.