In vitro anti-HIV-1 antibody production in subjects in different stages of HIV-1 infection

Abstract

SUMMARY We evaluated the in vitro antibody production from peripheral blood mononuclear cells (PBMC) against HIV‐1 proteins in infected adults. Fifty‐four HIV‐1 infected patients (four recent seroconverters, 15 asymptomatics with a CD4 count higher than 500/μl, 27 asymptomatics with a CD4 count between 200 and 500/μl and eight symptomatic patients) were tested. PBMC were incubated in the presence or absence of 1% pokeweed mitogen (PWM) at 37°C for 8 days. Western blot assay, p24 antigen ELISA and anti‐p24 antibody ELISA were performed on serum and culture supernatants. Spontaneous production of anti‐env antibody in culture supernatants was evidenced in all subjects. All the positive supernatants for anti‐core antibodies (18/54) were derived from asymptomatic patients. PBMC from recent seroconverters and from symptomatic patients did not produce any anti‐core antibody. Antibody production decreased after stimulation with PWM. The concentration of p24 antigen did not significantly increase in p24 positive supernatants following acidification (P= 0·1), suggesting that the inability to detect p24 antibody was not due to the anti‐p24 antibody complexed to p24 antigen in culture supernatants. In vitro production of anti‐p24 antibodies was significantly more frequent in asymptomatic subjects with high CD4+ cell counts (P= 002) and was absent in recent seroconverters. This last finding suggests that during the initial phases of the infection, anti‐p24 antibody production may be restricted to cells residing in lymphoid organs. In addition, the lower percentage of anti‐core antibody in people with low CD4+ cell counts is not merely a consequence of the binding of the antibody to an increased amount of antigen, but probably reflects an impaired production or a sequestration of producing cells in lymphoid tissue during the late stages of the infection.