Susceptibility of peripheral blood mononuclear cells to apoptosis is correlated to plasma HIV load

Objectives: To quantify spontaneous and activation-induced apoptosis in peripheral blood mononuclear cells (PBMC) of HIV-infected patients and to look for correlations between PBMC apoptosis levels, stages of HIV disease, CD4 count, and plasma viral load. Study Populations: 75 consecutive inpatients and outpatients infected with HIV (mean CD4 count, 202 +/- 182 x 10(6)/L; mean plasma viral load, 4 +/- 1.29 log(10) RNA copies/ml) and a control group composed of 18 healthy, HIV-negative adults. Methods: Spontaneous apoptosis was detected at the single-cell level by direct incorporation of fluorescein-deoxyuridine triphosphate (dUTP) in PBMC DNA strand breaks. Activation-induced apoptosis was determined after in vitro stimulation with anti-CD3 antibodies and interleukin-2 (IL-2). Results: Spontaneous apoptosis was low in patients and controls, whereas activation-induced apoptosis was significantly higher in HIV-infected patients (5.22 +/- 4.32% versus 2.46 +/- 1.77%, respectively; p = .009). The degree of activation-induced apoptosis was positively correlated with the plasma viral load (r = 0.29; p = .029) and negatively correlated with the CD4 count (r = -0.37,p = .0009). Although activation-induced apoptosis was significantly higher in patients fulfilling AIDS criteria, it did not differ significantly between patients with an acute AIDS-defining event and those with stable disease. Conclusion: Susceptibility of PBMC to apoptosis in HIV-l-infected patients is correlated to the plasma viral load and the stage of the disease.