FIG. 3.

Kinetic analysis of macrophage activation. Peritoneal cells from infected animals were collected at different time points of infection, cultured, and used to assess their ability to secrete nitrite in response to LPS (A) or superoxide in response to PMA (B). The open symbols represent the results from mice infected with strain 2447, and the closed symbols represent those from mice infected with strain 25291. Each value represents the mean ± 1 standard deviation of triplicates from a pool of cells from four mice. ∗, P < 0.05; ∗∗, P < 0.01.