Chemokine receptor expression on B cells. Representative staining histograms for chemokine receptor expression on total CD19⁺ B cells, from one control (top panel) and one HIV-1 patient (bottom panel). An acquisition forward/side scatter dot plot was used to gate live lymphocytes, and chemokine receptor expression was analyzed on B cells (A). (B-E) The expression of chemokine receptors on CD19⁺ B cells is shown as median fluorescence intensity (MFI); in the left panels, the expression of the CXCR5 (B), CXCR4 (C), CXCR3 (D), and CCR7 (E) in patients (n = 30) and controls (n = 30) is shown. The receptor expression in groups of patients divided according to their CD4⁺ T-cell count (< 350 cells/μL or > 350 cells/μL) is shown in the right panels. CXCR5 expression (B) on B cells from HIV-1–infected is decreased (P = .012) compared with controls, and CXCR5 expression was also significantly lower in patients with low CD4⁺ T-cell count (P = .04). There were no significant differences in the expression of CXCR4, CXCR3, and CCR7 between patients and controls. The expression of CCR7 (E) was increased in patients with low CD4⁺ T-cell counts (P = .004).