Balanced expression of CXCR5 and CCR7 determines positioning of T cells to the T-cell area or B-cell follicles. Immunohistology of cryostat sections from dLNs of mice immunized 4 days earlier with OVA plus CT that had also received lymphocytes from CXCR5^+/+DO11.10 (A), CXCR5^-/-DO11.10 (B), or CCR7^-/-DO11.10 (C) mice. LN sections were stained with KJ1-26 (green), anti-B220 (blue), and anti-CD3 (red). Data are representative for 3 mice analyzed per group. Further details are given under “Expression of CXCR5 and positioning in situ.”