Primary in vitro sensitization of human T-helper lymphocytes by peptides derived from the V3 loop of human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein.

To generate CD4+ T-helper cell lines, lymphocytes from HIV-seronegative subjects were primed in vitro with peptides derived from the V3 loop of HIV-1 gp120. Antigen-specific reactivity was inhibited by an anti-DR monoclonal antibody, indicating HLA-class II dependency, but peptides could be recognized in different HLA-class II contexts. Three sites on V3LAI and two on V3MN were identified as targets of the respective V3LAI- and V3MN-specific lines. Recognition of V3 peptides was isolate-specific. The lines did not react against whole gp160, which suggests that V3 may be differently presented when used as such rather than as part of the entire glycoprotein. Similar results were obtained in chimpanzees immunized in vivo against V3LAI.