(A) PBMCs and BAL fluid from patients with allergic asthma or DC were stained for Spry2 and CD4, then analyzed by flow cytometry. Frequency of Spry2+ CD4+ T cells was analyzed by Mann–Whitney U test (n = 8 donors/group). (B–E) Effect of shRNA-mediated knockdown on Spry2 expression (B), CD4+ T cell proliferation (C), and cytokine production under Th1- (D, E), Th2- (D), or Th17- (D) skewing conditions. Significance * p < 0.05, paired t test, (n = 4/group). All the data of this figure can be found in the S1 and S2 Data files. BAL, bronchoalveolar lavage; CPM, counts per minute; DC, disease control; IFN-γ, interferon gamma; PBMC, peripheral blood mononuclear cell; shLuc, luciferase shRNA; shRNA, short hairpin RNA; shSpry2, Spry2 shRNA; Spry2, Sprouty2.