Flow-cytometric analysis of B-cell subsets.Representative dot-plots of the flow cytometric analysis of circulating B cells (CD19⁺CD3^neg), according to the surface expression of IgD and CD27. Age-matched individuals are shown. Data refer to one seronegative (31 years old, 778 CD4⁺ T cells/μl), one untreated HIV-2-infected (34 years old, 321 CD4⁺ T cells/μl, undetectable viremia), one treated (ART) HIV-2-infected (34 years old, 326 CD4⁺ T cells/μl, undetectable viremia) and one untreated HIV-1-infected (30 years old, 306 CD4⁺ T cells/μl, 1814256 HIV-1 RNA copies/ml) individuals. Numbers inside quadrants represent the proportion of B cells expressing the respective markers. ART, antiretroviral therapy; IgD, Immunoglobulin D.