FIG. 6.
Unlike anti-gp120CD4BD MAbs, anti-CD4 MAbs have no effect on gp120 uptake and processing by APCs. (A) APCs were treated (dotted bars) or not treated (solid bars) with MAb RPA-T4 (10 μg/ml), an anti-CD4 MAb that can block gp120-CD4 interaction, and then were pulsed with gp120, with gp120 complexed with anti-C5 (450-D) or anti-gp120CD4BD MAbs (654-D and 559/64D), or with no antigen. These APCs were used to stimulate the gp120-specific CD4 T-cell line DMg26. T-cell proliferation was measured by [3H]thymidine incorporation. Recombinant gp120SF2 (3 μg/ml) was used either alone or mixed with anti-gp120 MAbs (10 μg/ml). (B) APCs were preincubated either with anti-CD4 MAbs capable of blocking gp120 binding to CD4 (SIM.4 and RPA-T4) or with a nonblocking anti-CD4 MAb (OKT4) and then pulsed with gp120. Each anti-CD4 MAb was used at 10 μg/ml. These APCs were tested in ELISPOT assays for the capacity to present gp120 antigen and induce IFN-γ production in DMg26 cells. In each of these experiments, autologous BCL was used as APCs.