Phenotypic characteristics and tendency to apoptosis of peripheral blood mononuclear cells from HIV+ long term non progressors.

The aim of this study was to analyze (i) phenotype, (ii) in vitro spontaneous and induced apoptosis, (iii) glutathione (GSH) intracellular content and (iv) inhibitors of apoptosis of potential therapeutical use in peripheral blood mononuclear cells (PBMC) from HIV+ long term non progressors (LTNP), in comparison with progressors (HIV+P) and seronegative controls (HIV-). Three groups of subjects were studied: 15 HIV+P (patients losing >150 CD4+/year), 9 LTNP (subjects infected by HIV for at least 7 years without clinical and immunological signs of progression, with a mean of 898 CD4+/microL) and 18 HIV-. All subjects were living in a large community for former drug addicts, and were matched for age and sex. We used flow cytometry for analyzing PBMC phenotype and apoptosis; high performance liquid chromatography for measuring intracellular GSH content. PBMC phenotype of LTNP shared characteristics with those of both HIV- and HIV+P. Indeed, LTNP showed a normal number CD4+ cells (an inclusion criteria), but significantly increased numbers of CD8+ lymphocytes, activated T cells, CD19+, CD5+ B lymphocytes and CD57+ cells, as well as a decrease in CD19+, CD5- B lymphocytes and CD16+ cells. In LTNP, spontaneous apoptosis was similar to that of HIV- and significantly lower than that of HIV+P. Adding interleukin-2 (IL-2) or nicotinamide (NAM) significantly decreased spontaneous apoptosis in LTNP and HIV+P. Pokeweed mitogen-induced apoptosis was also similar in LTNP and HIV-, but significantly lower than that of HIV+P. In HIV+P, but also in LTNP, spontaneous apoptosis was inversely correlated to the absolute number and percentage of CD4+ cells and directly correlated to the number and percentage of activated T cells present in peripheral blood. GSH intracellular content was greatly decreased in PBMC from HIV+P and slightly, but significantly, reduced in LTNP. Adding 2-deoxy-D-ribose, an agent provoking apoptosis through GSH depletion, to quiescent PBMC resulted in similar levels of massive cell death in the three groups. This phenomenon was equally prevented in the three groups by N-acetyl-cysteine but not by IL-2. A complex immunological situation seems to occur in LTNP. Indeed, PBMC from LTNP are characterized by a normal in vitro tendency to undergo apoptosis despite the presence of a strong activation of their immune system, unexpectedly similar to that of HIV+P. Our data suggest that NAM and IL-2 are possible candidates for reducing spontaneous apoptosis in HIV infection.