CD3,CD8 Double-Positive Cells from HIV-1-Infected Chimpanzees Show Group-Specific Inhibition of HIV-1 Replication

The CD8-positive (CD8⁺) lymphocyte population in the chimpanzee is composed of two major subsets, a CD3-positive, CD8-positive (CD3⁺CD8⁺) and a CD3-negative, CD8-positive (CD3^-CD8⁺) population. The aim of this study was to delineate the function of CD3⁺CD8⁺ T cells with respect to inhibition of HIV-1 replication. It could be shown that this cell population had the capacity to control the growth of HIV-1 in exogenously infected CD4-positive (CD4⁺) lymphocytes. This effect was observed only with cells from HIV-1-infected chimpanzees, was operative only in an autologous and not in a homologous situation, and was not due to cytotoxicity. CD3⁺CD8⁺ lymphocyte-mediated inhibition of HIV-1 replication was group-specific in that CD3⁺CD8⁺ cells of HIV-1 (IIIB)-infected chimpanzees were capable of inhibiting replication of HIV-1 strains IIIB, MN, and RF. The effect observed was operational during the early stages of HIV-1 replication only; the effector cells had to be added to CD4⁺ cells within 3 days after HIV-1 infection in order to suppress growth of the virus. The presence of CD3⁺CD8⁺ lymphocytes with anti-HIV-1 activity in the circulation of HIV-1-infected chimpanzees might contribute to the lack of progression toward AIDS observed in this species.