Fig. 3

TREG cells lacking β2-AR expression exhibit decreased intracellular cAMP levels and TREG cell suppressive function. TREG cells (CD4⁺CD25⁺) with (WT TREG) or without (β2-AR^−/− TREG) β2-adrenergic receptors were negatively isolated and; (a) assessed for cyclic-AMP levels after lysing using RIA. (n = 5 in triplicate) *P ≤ 0.05 between groups where indicated. b co-cultured with wildtype CD4⁺CD25⁻ naive Th cells using artificial Th cell activation (anti-CD3 and anti-CD28) for 72 h. Th cell proliferation was assessed using 3H–thymidine incorporation. *P < 0.01 for repeated measures ANOVA analysis. All data are shown as mean +/− SEM of triplicates for three independent experiments