DIFFERENTIAL EFFECT OF HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION ON THE IGA AND IGG ANTIBODY-RESPONSES TO PNEUMOCOCCAL VACCINE

The IgA,IgM, and IgG antibody responses to pneumococcal polysaccharide vaccine were analyzed in 35 asymptomatic or mildly symptomatic human immunodeficiency virus (HIV)-infected patients stratified according to their CD4 cell counts and in 12 healthy controls. Both the antibody t iters in serum and saliva and the numbers of circulating antigen-speci fic antibody-producing cells (Elispot technique) were measured. At the peak of the antibody responses, HIV-infected patients mounted nearly normal IgG responses, while their IgM responses were significantly dep ressed, regardless of their CD4 cell counts. The IgA antibody response was decreased in patients with < 500 CD4 circulating cells/mm(3). Mos t IgG antibodies belonged to the IgG2 subclass, and most IgA antibodie s were dimeric IgA2 in both controls and patients. Anti-capsular pneum ococcal polysaccharide IgG titers decreased much more rapidly in HIV-i nfected patients so that in all groups they were significantly lower t han in controls 9 months after vaccination.