Activation and maturation of peripheral blood T cells in HIV‐1‐infected and HIV‐1‐uninfected adults in Burkina Faso: a cross‐sectional study

Background We wanted to explore to what extent environmental exposure to immune stimulants, which is expected to be more present in rural than in urban settings, influences T cell activation and maturation in healthy and in HIV‐1‐infected individuals in Burkina Faso in west Africa. Methods The proportion of circulating naïve T cells and the expression of the T cell activation markers, CD95 and CD38, were analyzed by immunophenotyping and three‐colour flow cytometry in 63 healthy individuals and 137 treatment‐naïve HIV‐1‐infected subjects from Ouagadougou (urban setting) and 26 healthy adults and 61 treatment‐naïve patients from Nouna (rural). Results A slightly higher activation level of CD4+ and CD8+ peripheral blood T cells was seen in healthy adults living in Nouna than in those living in Ouagadougou. The percentages of naïve CD45RAbright CCR7+ T cells were not significantly different between both study sites. Taking into consideration that relatively more HIV‐1‐infected patients in Nouna were in an advanced disease stage, no relevant differences were seen in T cell activation and maturation between patients at both study sites. As expected, the percentage of CD95+ CD4+ and CD38+ CD8+ T cells and the respective antigen density on these cells was significantly higher in patients than in controls in both settings. The percentage of naïve CD8+ T cells was lower in HIV‐1‐infected subjects than in healthy controls irrespective of the study site, while a lower proportion of naïve CD4+ T cells in patients compared with controls was seen only in Nouna. Conclusions Environmentally triggered immune activation may contribute to the increased expression of the activation markers CD95 and CD38 on peripheral blood T cells from healthy adults living in rural versus urban settings in Burkina Faso. T cell activation is further increased in HIV‐1‐infected individuals due to T cell loss and high plasma viral load levels. The observed variations in T cell activation levels or the proportion of naïve T cells in our study patients, however, are not explained by differences in CD4+ T cell counts or HIV‐1 plasma viral load levels alone.