The effects of anti-CD80, anti-CD86, and anti-CD72 MoAbs on accessory function of AM isolated from the BAL of nine patients with HIV infection (two patients with AIDS-related complex and seven patients with full-blown AIDS). The above quoted antibodies, when added to assays at the beginning of culture, significantly inhibited the mitogen-induced proliferation of highly purified T cells. AM and T cells were enriched as reported in the Materials and Methods section.