Objective: To determine plasma cytokine levels [tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta and IL-6] in African patients infected with HIV-2 relative to values in HIV-1-infected patients, and their relation to immunologic and clinical status.
Design: Questions about the observed differences in the pathogenesis of HIV-2 and HIV-1 remain unanswered. Cytokines, especially TNF-alpha, are involved in the regulation of HIV-1 replication, and can be found in the plasma of HIV-1-infected individuals. Therefore, we evaluated TNF-alpha, IL-1 beta and IL-6 levels in the plasma of African patients with different stages of HIV-2 disease. This was a 3-year prospective follow-up study.
Methods: Cytokine plasma levels were assayed in 40 HIV-2- and 51 HIV-1-infected patients from Africa. Nineteen of the 40 HIV-2-infected-patients underwent serial assays every 4 months for 3 years. Data were analysed in relation to the number of CD4+ and CD8+ cells, viral load and clinical status.
Results: Plasma levels of TNF-alpha and IL-1 beta were significantly higher in all the HIV-1- and HIV-2-infected patients than in healthy controls; IL-6 levels were around the detection limit for all patients. TNF-alpha levels were lower in the HIV-2-infected than in the HIV-1-infected patients at all Centers for Disease Control and Prevention (CDC) disease stages, including the asymptomatic phase. The CD4+ cell count was always higher in the HIV-2-infected patients, regardless of CDC stage. The prospective follow-up showed that TNF-alpha levels remained stable during the course of HIV-2 disease, as did the CD4+ cell count and virus load.
Conclusion: Lower and stable plasma TNF-alpha levels in African patients infected with HIV-2, associated with lower viral load and higher CD4+ cell count, suggests the existence of a more appropriate and efficient immune response to HIV-2 than to HIV-1.