SE treatment leads to STAT3 phosphorylation and subsequent IL-17 secretion in primary T cells from CTCL patients. (A) Representative flow cytometric analysis of PBMCs freshly purified from a CTCL patient and cultured for 24 hours with SEA (200 ng/mL) or vehicle (PBS). After incubation, cells were stained for pY-STAT3 and CD3, CD4, and CD26. Nonmalignant T cells stain CD3⁺, CD4⁺, and CD26⁺, whereas malignant T cells stain CD3⁺, CD4⁺, and CD26⁻. (B) PBMCs from CTCL patients were stimulated with an SE cocktail of SEA, SEB, SEC2, SEE, SEI, and TSST-1 (200 ng/mL) or vehicle (PBS) for 24 hours. After incubation, IL17A expression and GAPDH expression were determined by qPCR. In each sample, IL17A expression is normalized to GAPDH. (C) Pooled data of PBMCs from CTCL patients stimulated for 24 hours with an SE cocktail of SEA, SEB, SEC2, SEE, SEI, and TSST-1 (200 ng/mL) or vehicle (PBS). IL-17A concentrations were determined by ELISA and normalized to 10⁶ cells. *P < .05. ND, not detected.