β₂AR-mediated lymphocyte retention depends on coupled chemokine receptors. (A and B) CFSE-labeled Ccr7^+/+ or Ccr7^−/− spleen cells were transferred to WT recipients, and 2 d later, the mice were treated with integrin-neutralizing antibodies for 18 h during continuous administration of saline or clenbuterol (40 mg/kg/day). Fractions of transferred CD4⁺ T cells (CD4⁺; A) and B cells (CD19⁺; B) remaining in mesenteric LNs were determined as ratios relative to those in saline-treated mice that did not undergo integrin blockade. Fold increases of remaining fractions by clenbuterol over saline treatment are shown in the right panels. (C and D) WT mice were treated s.c. with saline or AMD3100 (5 mg/kg), and 2 h later, CD4⁺ T cells (CD4⁺) and B cells (CD19⁺) in blood (C) and lymph (D) were quantified. (E–G) WT mice were treated with integrin-neutralizing antibodies for 18 h during continuous administration of saline, AMD3100 (40 mg/kg/day, E) or combination of AMD3100 and clenbuterol (40 mg/kg/day of each, F and G). Fractions of CD4⁺ T cells (CD4⁺, E and F) and B cells (CD19⁺IgD^hiCD95⁻, E and G) remaining in mesenteric LNs were determined as ratios relative to those in saline-treated mice that did not undergo integrin blockade. Fold increases of remaining fractions by clenbuterol treatment are shown in the right panels (F and G). Dashed lines show the levels of saline-treated control as a ratio of 1 (A, B, F, and G). Data are pooled from two experiments. Each symbol represents an individual mouse and bars indicate means. Sal, saline; Clen, clenbuterol. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns, not significant. P-values were obtained by one-way ANOVA with Bonferroni’s post-test (left panels of A, B, F, and G) or unpaired Student’s t test (C–E and right panels of A, B, F, and G).