Impairment of in vitro immune responses occurs within 3 months after HIV-1 seroconversion.

In a previous study we have shown that peripheral blood mononuclear cells (PBMC) from asymptomatic HIV-seropositive male homosexuals, who had seroconverted more than 2 years before, were unable to mount a secondary immune response in vitro to certain viral and bacterial antigens. We have extended this study by investigating the secondary immune responses of five male homosexuals, who, by regular screening, were found to have seroconverted for HIV-1 during the preceding 3 months and were subsequently vaccinated with tetanus toxoid and poliovirus vaccine. Six weeks after the booster vaccination, PBMC of the five recently seroconverted individuals were assayed for in vitro mitogen or recall antigen-induced antibody synthesis and lymphocyte proliferation. The results of this study indicate that certain of the in vitro abnormalities of immune reactions, observed in both symptomatic and asymptomatic HIV-seropositive individuals, can already be found within 3 months after seroconversion.