E. muris infection, but not IOE infection, induces immunoregulatory cytokine IL-10 in the spleen during the acute stage and TGF-β1 during the acute and chronic phases of the infection. (A and B) Splenocytes from mice infected with E. muris produced significantly greater quantities of IL-10 and TGF-β1 on day 7 after primary infection compared to IOE-infected mice and naive uninfected mice. Significantly greater quantities of TGF-β1 were produced by splenocytes from mice persistently infected with E. muris on day 36 after E. muris infection compared to splenocytes harvested from naive mice (B). The data are presented as means ± the standard deviations, and three mice per group are included for analysis. Asterisks indicate significant differences from the naive group. *, P < 0.05; **, P < 0.01; ***, P < 0.001.