Predominate HIV1-specific IgG activity in various mucosal compartments of HIV1-infected individuals.

Evaluating mucosal humoral immunity is important for understanding local immunity induced by HIV infection or vaccination and designing prophylactic strategies. To characterize the mucosal humoral immunity following HIV infection, the levels of immunoglobulins (Igs), antibodies (Abs), and HIV1-specific Ab activity were evaluated in cervicovaginal secretions (CVS), saliva, breast milk, and sera of HIV-infected individuals. HIV1-specific IgG activity was significantly higher than that of IgA in CVS, saliva, and breast milk. The highest HIV1-specific IgG activity was found in breast milk. The data suggest that anti-HIV1 Abs in CVS were most likely serum derived. However, HIV1-specific Abs in saliva and breast milk were mainly locally produced. The prevalence of HIV1-specific Abs in seropositive subjects was 97% for IgG and 95% for IgA in CVS, 100% for IgG and 80% for IgA in saliva, and 59% for IgG and 94% for IgA in breast milk. These data provide evidence for both a better understanding of the nature of humoral mucosal responses after HIV1 infection and the development of strategies to induce desirable functional mucosal immunity for preventing HIV transmission.