IGA IMMUNITY IN HIV TYPE 1-INFECTED CHIMPANZEES .1. SYSTEMIC IMMUNITY

HIV infection in humans causes various aberrancies in both the cellula r and humoral immune systems, including functional abnormalities of B lymphocytes. In many instances, dysfunction occurs in the regulation o f serum IgA, resulting in elevated concentrations of this immunoglobul in isotype. To determine whether HIV-1-infected chimpanzees develop Ig A abnormalities similar to those observed in humans, we quantified tot al IgA, IgG, and IgM levels in sera collected longitudinally from six HIV-infected chimpanzees and one uninfected control animal. In compari son to immunoglobulin levels in the uninfected animal, two of the six infected chimpanzees exhibited increases in serum immunoglobulins foll owing infection with HIV. Two other infected animals showed a marked d ecrease in the three isotypes within 10 months of exposure to HIV, fol lowed by a return to baseline levels. The remaining two HIV-infected c himpanzees displayed serum immunoglobulin levels that paralleled the b aseline levels and did not show great deviation over a period of 20 to 45 months postinfection. ELISA analyses of the IgA subclasses reveale d possible abnormalities of the IgA2 subclass within the two animals t hat did not display irregular IgA, IgG, or IgM responses to HIV-1. Spe cific IgG, IgA, IgA1, and IgA2 antibodies to HIV antigens were detecte d by an enzyme immunoassay (EIA) kit and by Western blot analysis with IgA, IgA1, and IgA2 antibodies directed against the env, gag, and pal gene products. Because IgG can mask the detection of HIV-specific IgA antibodies in infected humans, Western blots and EIAs were also perfo rmed on IgG-depleted chimpanzee sera. The results demonstrated that in some instances, IgA reactivity against HIV antigens can be enhanced o n removal of IgG, This study indicates that HIV-1 is capable of induci ng abnormalities in serum IgA expression in chimpanzees. These results might further understanding of how HIV affects humoral responses in i nfected humans.