Arginase activity in cells harvested from the peritoneal cavity of EA-treated mice after culture in the presence of IL-4. Mice were treated with EA (15/30 Hz) at the Zusanli acupoint (ST36) for 20 min/d for 5 d (A and C) or 10 d (B). After the final EA session, the mice were euthanized and their peritoneal cells were harvested and cultured in the absence (medium) or presence of IL-4 at 5 ng/mL (A and B) or 25 ng/mL (C). After 48 h, the culture medium was discarded, and the cells were lysed for evaluation by the arginase assay. The data are represented as mean ± SD of urea production per lysate of 1 × 106 cells. The sham-treated mice received only needle insertion into a non-acupoint (gluteal muscle) without electrical stimulation. There were nine mice in each group. *P < 0.05, significant difference between sham- and EA-treated mice under the same culture conditions by Student’s t-test.