Memory B-cell depletion is a feature of HIV-2 infection even in the absence of detectable viremia

Objective: Memory B-cell loss has long been recognized as an important contributor to HIV immunodeficiency. HIV-2 infection, which is characterized by a slow rate of progression to AIDS and reduced to undetectable viremia, provides a unique model to investigate B-cell disturbances. DESIGN AND Methods: B-cell subsets were evaluated in 38 HIV-2-infected individuals, along with markers of T-cell activation and serum levels of immunoglobulins and a major B-cell homeostatic cytokine, B-cell activating factor (BAFF). Untreated HIV-1-infected and seronegative control individuals were studied in parallel. Statistical analysis was performed using Mann-Whitney tests and Spearman's correlations. Results: We found that HIV-2 was associated with significant depletion of both unswitched (CD27IgD) and switched (CD27IgD) memory B-cells that directly correlated with T-cell activation, even in individuals with undetectable plasma viral load. Nevertheless, the presence of detectable viremia, even at low levels, was associated with significant memory B-cell loss and higher BAFF levels. Moreover, these alterations were not recovered by antiretroviral- therapy, as treated HIV-2-infected patients showed more pronounced B-cell disturbances, possibly related to their extended length of infection. Conclusion: These first data regarding B-cell imbalances during HIV-2 infection show that, irrespective of viremia, prolonged HIV infection leads to irreversible damage of memory B-cell homeostasis.