An anti-gp41 human monoclonal antibody that enhances HIV-1 infection in the absence of complement.

B lymphocytes from tonsillar tissue of an asymptomatic HIV-1-seropositive subject were transformed with Epstein-Barr virus (EBV) and tested for the production of HIV-1-specific antibodies by ELISA, using purified HIV-1SF2.2F11, a monoclonal antibody derived from a transformed line, is of the IgG1 subclass and recognizes an epitope in the conserved region of the envelope transmembrane glycoprotein gp41, which is expressed on the surface of HIV-infected T cells. The antibody does not mediate the lysis of infected T cells in antibody-dependent cellular cytotoxicity (ADCC) assays and does not neutralize the infectivity of HIV-1SF2 or the homologous isolate HIV-1TT2.2F11 appears to be the first anti-gp41 human monoclonal antibody that enhances the infectivity of an HIV-1 strain (i.e., SF128A) in the absence of complement.