FIG 3.

Intraperitoneal injection of rIFN-α enhanced C. burnetii-induced weight loss. (A) When wild-type mice were treated with rIFN-α by i.p. injection and infected with 10³ GE C. burnetii, the higher dose of rIFN-α promoted C. burnetii pathogenesis. When this high dose was delivered to uninfected mice, there was no change in weight. The lower dose of rIFN-α did not affect weight loss compared to saline-treated mice. (B and C) There were no differences induced by IFN-α treatment (IFNtx) in bacterial quantities in lungs or spleens 9 (B) or 6 (C) days postinfection. (D) Following infection with 10² bacteria and high-dose rIFN-α treatment, cytokines in BAL fluids and serum were assessed. The only two cytokines that changed significantly were G-CSF and IL-1β in BAL fluid. These cytokines were not detected in day 1 and day 3 untreated infected mice. They were present in PBS-treated mice at day 6 postinfection and decreased in response to i.p. rIFN-α treatment. The data are representative of the results of at least 2 replicate experiments. *, P < 0.05; ****, P < 0.0001; ns, not significant.