Expression of CXCR5 and CCR7 and positioning of T cells to B-cell follicles in LNs and PPs. Peripheral LNs (right column) and PPs (left column) from C57BL6 mice were stained with anti-CD4-PerCP, anti-CXCR5 followed by mouse anti-rat-Cy5 and a CCL19-IgG fusion protein detected with goat anti-human-IgG-PE to reveal CCR7 expression (upper panel). The expression of CXCR5 and CCR7 is shown for CD4⁺ cells. The central panel shows corresponding isotype controls (1H4; and a nonbinding CCL25-IgG fusion). Immunohistology of cryostat sections from pLNs and PPs using anti-B220 (blue) and anti-CD3 (red). Data are representative for 6 mice. Comparable results were obtained analyzing 4 Balb/c mice.