Lymphoproliferative response to HIV type 1 p24 in long-term survivors of HIV type I infection is predictive of persistent AIDS-free infection

To establish immunologic correlates of progression to AIDS in long-term sur vivors of HDV-1 infection, HIV-1-specific T cell-mediated responses, togeth er with T cell reactivity to recall antigens, were studied in frozen sample s collected after 5 and 8 years of documented HIV-1 infection. Eight of 21 homosexual men, who remained asymptomatic and maintained CD4(+) T cell numb ers >400 cells/mu l for 9 years of HIV-1 infection, progressed to AIDS (CDC 1993 definition) within 12.5 years of infection (late progressors, LPs). T he remainders showed minimal deterioration of immune parameters (long-term nonprogressors, LTNPs). CD4(+) T cell numbers and T cell function measured at years 5 and 8 of follow-up were comparable in the two groups. At both ti me points responses to recall antigens did not significantly differ between the two groups, although a significant decline of lymphoproliferative resp onses to Candida and tetanus toroid was observed in Lps. Circulating HIV-1- specific cytotoxic T lymphocyte precursors were found in broad frequency ra nges in both Ups and LTNPs and, similarly, no significant differences were found in comparing the breadth of serum neutralizing activity against heter ologous HIV-1 primary isolates. In contrast, lymphoproliferative responses to p24(gag), but not p17(gag) or gp160(env), were detected only in LTNPs an d were totally absent in LPs at both time points (p < 0.01). Our data sugge st that the presence of circulating p24-specific CD4(+) T cells may reflect effective viral control and be predictive of subsequent favorable clinical course in long-term asymptomatic individuals.