Normalization of B Cell Counts and Subpopulations after Antiretroviral Therapy in Chronic HIV Disease

Background. Untreated human immunodeficiency virus (HIV) disease leads to abnormalities in all major lym-phocyte populations, including CD4 T cells, CD8 T cells, and B cells. However, little is known regarding the effect of antiretroviral therapy (ART)–induced decrease in HIV viremia on B cell numbers and subpopulations. Methods. We conducted a longitudinal study to evaluate changes in B cell numbers and subpopulations that occur during the course of 12 months of effective ART in a group of individuals with chronic HIV infection. Results. ART-induced decrease in HIV viremia was associated with a significant increase in B cell counts, similar to increases in CD4 T cell counts yet distinct from the lack of increase in CD8 T cells. The increase in B cell counts was accompanied by a significant decrease in the frequency of apoptosis-prone B cell subpopulations, namely mature activated and immature transitional B cells, which are overrepresented in untreatedHIV disease. The increase in B cell counts was reflected by a significant increase in naive and restingmemory B cells, both of which represent populations that are essential for generating adequate humoral immunity. Conclusions. Normalization of B cell counts and subpopulations may help to explain the improvement in hu-moral immunity reported to occur after an ART-induced decrease in HIV viremia. Untreated HIV disease is associated with perturbations of all major lymphocyte populations, including B cells