CD16+ NK Cells Decrease in All Stages of HIV Infection Through a Selective Depletion of the CD16+CD8+CD3- Subset

Natural killer (NK) cell-related phenotypes were analyzed in human immunodeficiency virus (HIV) infection. Our study involved 168 HIV-infected patients (72 CDC Stage II, 48 Stage III, and 46 Stage IV) and 60 healthy individuals. Analyses were conducted using flow cytometry and monoclonal antibodies. In comparison to the control group, all patient groups showed a significant decrease (p < 0.001) of the CD16+ and CD16+CD3- phenotypes; furthermore, the comparison among patient groups showed no significant difference. It seems, therefore, that the decrease begins in the asymptomatic stage (CDC II) and remains constant during the infection. CD16+ NK cells were further divided into two subsets: CD16+CD8+ and CD16+CD8-. This subdivision shows a severe selective depletion of the CD16+CD8+ subset, but not in the CD16+CD8- subset. The depletion of the CD16+CD8+ subset also appears in the CDC asymptomatic stage and remains constant in CDC stages III and IV. Elsewhere, we observed that CD16+CD8+ lymphocytes are CD3-; complementary analysis of CD3-CD8+ cells showed a depletion comparable to that of the CD16+CD8+ phenotype. Depletion of the CD3-CD8+ subset, which belongs to the NK cell compartment, was observed although the total CD8 population showed a statistically significant increase. We conclude that, in HIV infection, there is a quantitative decrease of the NK CD16+ cell population, which appears to be due to a selective depletion of the CD16+CD8+CD3- compartment. This severe depletion appears to begin early in the infection.