SE-mediated expression of IL-10 by primary malignant T cells requires the presence of benign T cells. (A-C) Malignant T cells were purified from the blood of SS patients and cultured for 24 hours with vehicle (PBS) or SEA (200 ng/mL) as well as (A) benign T cells purified from the blood of SS patients, (B) the benign CTCL T-cell line MF1850, or (C) a CD4 T-cell line established from the blood of a healthy donor (HD). Depicted is the concentration of IL-10 in the cell culture supernatants per 1 × 10⁶ malignant T cells as measured by ELISA. Malignant T cells from 3 (A,C) and 4 (B) different patients were analyzed. Error bars represent SEM.