IMMUNOGLOBULIN CLASS AND SUBCLASS ANTIBODIES TO HIV PROTEINS IN MATERNAL SERUM - ASSOCIATION WITH PERINATAL TRANSMISSION

A flow cytometry-based assay for detection of immunoglobulin (Ig) clas s and subclass antibodies in human serum or plasma was developed. With use of this procedure, the presence and relative frequency of antibod y activity in the Ig classes and subclasses (IgA1, IgA2, IgD, IgE, IgG 1, IgG2, IgG3, IgG4, and IgM) to human immunodeficiency virus type 1 ( HIV-1) proteins (gp160, gp120, p66, and p24) was determined in serum o r plasma from a cohort of 47 HIV-1-infected, pregnant women. Antibody activity in each of the classes and subclasses was found with differen ces in frequency depending on the Ig class/ subclass and the HIV-1 pro tein. IgG1 antibodies were the most frequently reactive Ig class/subcl ass to each protein. Intermediate frequencies of reactivity were found in IgA1, IgG2, IgG3, and IgM class and subclasses and antibodies of t he IgA2, IgE, and IgG4 class/subclass the least frequently detected. A n unexpected finding was the presence of IgD antibodies to HIV-1 prote ins in similar to 50% of the individuals. The distributions of Ig clas s/subclass antibodies to the different HIV-1 proteins were compared in sera from 14 mothers giving birth to infants who were determined to b e HIV-1 infected with sera from 25 individuals whose infants were not infected. Sera from transmitting mothers contained a broader distribut ion of class and subclass antibodies compared to sera from nontransmit ting women. The single most frequent antibody-antigen combination that was found in the transmitting mother was IgG2-gp160. Combinations of IgG1-IgG2, IgD-IgG2 antibodies to gp160 and IgA1-IgE antibodies to p66 were present more frequently in transmitters compared with the same c ombinations in nontransmitting mothers' sera. Whereas the significance of these findings are not apparent, increased activity of class and s ubclass antibodies in transmitting mothers suggest the possibility tha t previously described antibody-mediated enhancement may be operative in HIV-1 mother-infant transmission.