RIAM-deficient lymphocytes traffic efficiently to spleen but not pLNs or BM. (A) Brachial, axillary, and inguinal lymph nodes removed from RIAM^+/+ or RIAM^−/−mice. Scale bar represents 5 mm. (B, D) Numbers of T and B cells recovered from pLNs (B) or spleens (D) of RIAM^+/+ or RIAM^−/−mice. Plotted are mean ± SD; n = 7; *P < .05, **P < .01. (C, E) Thin sections of inguinal and brachial pLNs (C) or spleens (E) from RIAM^+/+ or RIAM^−/− mice stained for B cells (B220), T cells (CD3), and stromal cells (F480). Bar represents 100 μm. (F) Numbers of T and B cells in the peripheral blood of RIAM^+/+ or RIAM^−/−mice. Plotted are mean ± SD; n = 4. (G) Numbers of red (CMTMR stained RIAM^+/+) or green (carboxyfluorescein diacetate succinimidyl ester stained RIAM^−/−) CD3⁺ T cells and CD19⁺ B cells detected by flow cytometry in the spleen, pLNs, BM, and blood of RIAM^+/+ recipients 3 hours after intravenous injection of equal numbers of stained, red blood cell-depleted splenocytes. On the left is a representative cytofluorimetric scatter plot of CD19⁺ cells, and on the right are cumulative data plotted as the mean ± SD of the ratios of green:red cells; n = 9; ***P < .001, ****P < .0001.