PRIMARY IN-VITRO IMMUNIZATION WITH MULTIMERIC SYNTHETIC PEPTIDES OF HIV-1 ENVELOPE GLYCOPROTEINS - GENERATION OF NEUTRALIZING HUMAN MONOCLONAL-ANTIBODIES

Peripheral blood lymphocytes from healthy HIV-1 seronegative donors we re immunized in vitro with the following synthetic peptides: (i) an oc tameric poly-L-lysine conjugated peptide of the HIV-1(MN) V3 loop and (ii) a resin bound synthetic peptide aa642-665 of HIV-1 gp41. Lymphobl astoid cell lines (LCL) were obtained by immortalization with Epstein- Barr virus (EBV). We produced four LCL secreting human monoclonal anti bodies (HuMoAbs) of the IgM isotype: three were directed against the V 3 domain (FC10, FC81 and CF41) and one against aa642-665 (CA45C). Two of these HuMoAbs (FC81 and CA45C) reacted to viral surface antigen on HIV-1-infected cells. All the HuMoAbs inhibited 40-53% of cell fusion induced by HIV-1-infected H9 cells at 5 mu g/ml. They also neutralized , at lower concentrations, cell-free infection with HIV-1(MN), HIV-1(I IIB) and four primary clinical HIV-1 isolates. No enhancing activity o f the HuMoAbs in the presence of complement was observed. The results presented here show the feasibility of generating neutralizing human m onoclonal antibodies against HIV-1 by primary in vitro immunization wi th selected synthetic peptides of HIV-1 envelope glycoproteins. This a pproach has provided tools for further studies of synergistic neutrali zation assays, and generated potential immunoglobulin candidates for p assive immunotherapy.