Comparative analysis of apoptosis in HIV-infected humans and chimpanzees: relation with lymphocyte activation.

Programmed-cell death (apoptosis) is a physiological cell death process which appears exacerbated in peripheral lymphocytes from HIV-infected persons. On the contrary, a barely detectable level of apoptosis is found in peripheral lymphocytes from HIV-infected chimpanzees, which support long-term productive infection without developing AIDS. In the present study, we analyzed the relationship between apoptosis and the general state of immune activation in PBMC from HIV-infected humans and chimpanzees. In addition, apoptosis control in the CD8 subset by the bcl-2 proto-oncogene was compared in both human and chimpanzees. Taken together, the results indicate that the degree of apoptosis correlates with the state of activation of the immune system and this observation together with the finding that apoptosis concerns all lymphocyte subsets indicates that the low level of apoptosis in HIV-infected chimpanzees is related to the lack of immune activation in this nonpathogenic model.