Time course of the changes in blood cell counts induced by IL-18.

IL-18 (2 μg/mouse) was injected into 5 BALB/c mice subcutaneously once a day for 5 weeks. Five control mice were injected with PBS. Blood cells were counted after Diff-Quick (Midori) staining. Open circles show the control group and closed circles show the IL-18–treated group. Black bars inserted in each figure show the period of IL-18 treatment. Dotted lines show the changes of cell counts after the withdrawal of IL-18 treatment. Bars represent SE of 5 mice. *P < .05 and ** P < .01, compared with the control of the corresponding time point (Dunnett test for multiple comparison).