FIG. 4.

Anti-gp120_CD4BD/gp120 complexes do not affect the capacity of APCs to take up, process, and present gp160_NL4.3 to the CD4 T cells. (A) Proliferation of gp120-specific CD4 T-cell line 027-563 was measured in response to APCs pulsed with gp160_NL4.3 in the presence or absence of anti-gp120_CD4BD/gp120 complex (6 μg of 654-D per ml + 2 μg of gp120_SF2 per ml). Recombinant gp160_NL4.3 has no CD4 binding activity and does not react with anti-gp120_CD4BD MAbs. HLA-DR-matched heterologous PBMCs were used as APCs. The background response to APCs alone (no antigen) was 500 cpm. (B) Presentation of gp160_NL4.3 was not affected by the addition of increasing concentrations of anti-gp120_CD4BD/gp120 complex. T-cell response to gp160_NL4.3 was assessed in the presence of different concentrations of the immune complex: 30 μg of 654-D per ml + 10 μg of gp120_SF2 per ml (open triangles), 10 μg of 654-D per ml + 3 μg of gp120_SF2 per ml (open diamonds), 3 μg of 654-D per ml + 1 μg of gp120_SF2 per ml (open circles), or no 654-D/gp120 complex (filled squares). To test a more homogenous population of APCs, an autologous BCL was used in this experiment. T-cell response to APCs with no antigen was 759 cpm.