Increased IgG⁺ naive B cells in HIV-1 infection. B cells were purified from 3 HIV-1–infected and 3 uninfected subjects. The intracellular content of IgG was measured in the total population of naive B cells (CD19⁺CD27^–, panels A,C) and in the activated naive B cells (CD70⁺CD27^–, panels B,D) by 3-color flow cytometry. One representative healthy control (C, D) and one HIV-1–infected patient (A, B) are shown. In panels B and D, the dotted line shows the isotype control Ab and the filled area shows the anti–IgG-CyChrome Ab.