Human immunodeficiency virus (HIV)-specific IgA and HIV neutralizing activity in the serum of exposed seronegative partners of HIV-seropositive persons

The presence and activity of human immunodeficiency virus (HIV)-specific an tibodies were analyzed in the sera of 15 sexually exposed seronegative pers ons who had systemic HIV-specific cell-mediated immunity and IgA-mediated m ucosal immunity and in their HIV-infected partners. The HIV-positive subjec ts had HIV-specific serum Ige and IgA; the seronegative persons had HIV-spe cific serum IgA in the absence of IgG, Testing of the seronegative persons 1 year after the interruption of at-risk sex showed that no Ige seroconvers ion had occurred and that HIV-specific IgA serum concentrations had decline d. Serum from the HIV-exposed seronegative persons was analyzed for the abi lity to neutralize primary HIV-1 isolates. Neutralizing activity was detect ed in 5 of 15 sera and in 2 cases was retained by serum-purified IgA, Thus, the immunologic picture for resistance to HIV infection should include HIV -specific cell-mediated immunity as well as HIV-specific IgA-mediated mucos al and systemic immunity.