Fig. 1.

Activin-A drives the differentiation of human Tr1-like cells. (A) Human naive CD4⁺ T cells were sorted from the peripheral blood of atopics; labeled with CFSE; and stimulated with allergen (mixed grasses extract)-loaded, mitomycin-treated, CD3-depleted APCs in the presence of PBS (control) or activin-A for 7 d (or 9 d for IL-10) and analyzed by flow cytometry. The percentages of cytokine-producing T cells are shown. Data are expressed as mean ± SEM and are pooled from n = 8 independent experiments (n = 8 donors). (B, Left) Representative FACS plots showing T-cell proliferation gated on CD4⁺ T cells. Max, maximum. (B, Right) Cumulative data pooled from n = 6–8 independent experiments (n = 8 donors). (C) Cytokines in culture supernatants are shown. Data are expressed as mean ± SEM of triplicate wells and are pooled from n = 8 independent experiments (n = 8 donors). (D) Representative FACS plots showing ICOS and IL-10 expression gated on CD4⁺ T cells. Cumulative data are pooled from n = 6–8 independent experiments (n = 8 donors). (E) Real-time PCR analysis of ICOS, LAG3, GZMB, and IL10 mRNA levels in CD4⁺ T cells stimulated as above for 3 d. Results are presented relative to GAPDH and are pooled from n = 5 separate experiments (n = 5 donors). (F) Representative FACS plots (Left) and percentages (Right) of LAG3⁺CD49b⁺ cells among CD4⁺IL-10⁺ICOS⁺ T cells are depicted. Data are pooled from n = 4–6 separate experiments (n = 6 donors). Statistical significance was obtained by the Student’s t test (*P < 0.05; **P < 0.01; ***P < 0.001).