Elevated expression of SOCS3 in patient-derived EBV-transformed cell lines. Expression of the STAT3-target SOCS3 was determined by quantitative RT-PCR in resting (A) and (B) IL-21–activated (50 ng/mL for 21 hours) cell lines. Increased SOCS3 transcript was detected in patient-derived cells compared with healthy controls (HC1 and HC2). Results represent the fold-increased expression in SOCS3 transcript compared with unstimulated healthy control 1 (HC1) and are normalized to β-actin. Results represent the mean ± SEM of 3 independent experiments. *P < .05; **P < .01; ***P < .001.