Fig. 4.

Arginase produced by peritoneal cells from infected mice prevents the re-expression of the CD3ζ chain. Isolated murine pan T cells were stimulated with 3 μg/ml anti-CD3ε plus 500 ng/ml anti-CD28 antibodies in l-arginine-free RPMI 1640 for 24 h, and peritoneal cells from infected/control mice were cultured in RPMI 1640 containing 300 μM l-arginine separately for 24 h. Stimulated T cells were then added to the upper chamber of a co-culture transwell system containing the peritoneal cells in the bottom chamber for an additional 48 h of culture. In some experiments, the l-arginine (2 mM), BEC (90 μM), l-NMMA (500 μM) and catalase (200 U/ml) were respectively added into the cultures at 0 h. a CD3ζ re-expression in CD4⁺ and CD8⁺ T cells was tested by flow cytometry. The differences were analyzed by a one-way ANOVA. b Representative histograms of CD3ζ re-expression in activated CD4⁺ and CD8⁺ T cells co-cultured with peritoneal cells for 48 h. The data are the result of one representative experiment out of three independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001. Abbreviations: ns, not significant