Clinical progression of HIV infection: role of NK cells

The purpose of the study was to examine how immune parameters related to non-major histocompatibility complex (MHC) restricted cytotoxicity changed with respect to progression and duration of human immunodeficiency virus (HIV) infection. Forty-one HIV seropositive subjects with a known time for seroconversion were included. The major finding was that a low percentage and number of natural killer (NK) cells were found in the group who had a rapid progression to acquired immune deficiency syndrome (AIDS) (less than 70 months following seroconversion) compared with those progressing more slowly to AIDS (more than 70 months following seroconversion). Furthermore, a significant correlation was found between the number of months from seroconversion to the diagnosis of AIDS and percentages of CD16+ cells (rs = 0.811, P < 0.01), CD56+ cells (rs = 0.647, P < 0.05), and CD16+CD56+ cells (rs = 0.839, P < 0.01) as well as the concentration of CD16+CD56+ cells in the blood (rs = 0.699, P < 0.05) No differences were found in percentages and concentrations of NK cell subsets between subjects with a long history (more than 6 years) versus a short history (less than 6 years) of HIV infection without AIDS. Furthermore, no negative correlations were found between the concentration of any NK subsets and the number of months since seroconversion in HIV seropositive individuals without AIDS. The total concentration of CD16+, CD56+, and CD16+CD56+ cells was lower in the group of HIV seropositive subjects compared with HIV seronegative subjects (age and sex matched), and the concentration of CD16+ cells was lower in those with AIDS than in those without AIDS. In conclusion, low concentration of NK cells in the blood was associated with a more rapid disease progression, indicating that defective non-MHC restricted cytotoxicity may be associated with HIV disease progression.