Fig. 1

Effect of transforming growth factor (TGF)-β on interleukin (IL)-13 production by T lymphocytes from healthy donors and patients with SSc. Freshly isolated peripheral blood lymphocytes (PBLs) from healthy donors (n = 8) and patients with systemic sclerosis (SSc) (n = 10) were cultivated with anti-CD3/anti-CD28 antibodies and IL-2 for 5 days, then stimulated with phorbol 12-myristate 13-acetate (P) + ionomycin (I) for 5 h and treated or not with TGF-β for the last 4 h. a Levels of IL-13 mRNA measured by RT-PCR analysis and frequency of IL-13 cells in b and d CD4⁺ and c and e CD8⁺ T cells were quantified by intracellular staining by fluorescence-activated cell sorting (FACS) analysis. The results are presented as mean percentage (±SD) of IL-13 expression measured in the presence of TGF-β (dark bars) relative to the respective IL-13 expression detected in the absence of TGF-β (white bars). *p < 0.05; ***p < 0.001. Representative FACS histograms are from one representative healthy control (left panel) and one representative patient (right panel) showing double staining of d CD4⁺IL-13⁺ and e CD8⁺IL-13⁺ cells gated on CD3⁺ T lymphocytes, previously treated or not with TGF-β, as measured by intracellular IL-13 staining and surface expression of CD4 or CD8