FcRL6 expression is dramatically up-regulated on lymphocytes in HIV-1–infected patients. (A) Two-color FACS analysis of blood from HIV-1⁺ patients and healthy controls shows relative increases in FcRL6⁺ lymphocytes in HIV-1⁺ individuals. FACS plots showing increases in CD8⁺ FcRL6⁺ cells and CD4⁺ FcRL6⁺ cells are representative of the median expression levels for healthy and infected individuals. Up-regulation of FcRL6 on B cells in HIV-1⁺ is also seen, though less frequently than for T cells. Cells are gated by FSC/SSC to include lymphocytes. (B) Three-color FACS analysis of CD8⁺ T cells in HIV-1⁺ individuals. CD8⁺ FcRL6⁺ T cells (upper plot) express 2B4 (lower histogram) and therefore correspond to the effector/effector-memory population. (C) The distribution of FcRL6⁺ cells among CD4⁺ and CD8⁺ T cells is shown. Dramatic and statistically significant increases in FcRL6⁺ can be seen in both major populations of αβ-T cells. Elevation in the number of FcRL6⁺ CD8⁺ or CD4⁺ T cells does not correlate significantly with viral titer or CD4 count (not shown). Horizontal lines indicate mean values.