Serum cytokine levels in mice treated with IL-18.

IL-18 (2 μg/mouse) was injected into 18 BALB/c mice subcutaneously once a day for 5 weeks. Cytokines in the serum were analyzed by ELISA systems. Open and closed columns show control mice injected with PBS and IL-18–treated mice (3 mice each), respectively. Bars represent SE (n = 3). Closed and open bars on the top of each panel indicate the period of IL-18 treatment and withdrawal, respectively. *P < .05, compared with control of the corresponding time point (unpaired Student t test).