QUANTIFICATION OF IGA AND IGG AND SPECIFICITIES OF ANTIBODIES TO VIRAL-PROTEINS IN PAROTID-SALIVA AT DIFFERENT STAGES OF HIV-1 INFECTION

Paired sera and parotid saliva from 75 HIV-1-infected patients, divide d in three equal groups with CD4(+) cell counts > 500, 200-500 and < 2 00/mm(3), respectively, were analysed for IgG, IgA and secretory IgA ( sIgA) concentrations and for IgG and IgA antibody directed to HIV-1. T wenty-nine age-matched HIV- subjects were used as controls. In serum t he concentrations of immunoglobulins were significantly increased in H IV-infected subjects compared with controls, and a progressive increas e of IgA and sIgA was noticed while the CD4(+) cell count decreased. I n contrast, concentrations of IgA and sIgA were not different in parot id saliva between the four subject groups. By an ELISA test directed t owards HIV-1 proteins, 73 of the 75 serum specimens from the HIV-infec ted subjects (97%) and 43 of the corresponding saliva (57%) were found positive for specific IgA antibodies to HIV-1, with an even distribut ion among the three groups of patients. By Western blotting multiple s pecificities of IgA to HIV-1 proteins were not frequently found in pat ients. By contrast, in spite of an IgG concentration in saliva about 1 00 times lower than that of IgA, reactivities were significantly highe r for IgG than for IgA antibodies, especially to env and to pol HIV-1 products. Altogether, these data suggest that the regulation of IgA pr oduction in HIV-infected subjects is independent in serum and in parot id saliva. This imbalance of IgA/IgG antibodies to HIV-1 at the mucosa l level appears to be a specific feature of HIV-1 infection, and may r aise important issues in terms of local protection after immunization.