Increased cytokine and chemokine levels in IL-18/IL-2–treated mice.

(A) B6 (n = 8 per group) mice were treated with control PBS, IL-2 (50 000 IU) alone, IL-18 (1 μg) alone, or IL-2 (50 000 IU) plus IL-18 (1 μg) once a day. At 6 hours after the third injection, mice were killed; the sera were immediately harvested; and serum cytokine levels were measure by ELISA. (B) B6 mice were treated with IL-2 (50 000 IU) plus IL-18 (1 μg) once a day for 4 days. At 2 hours after every injection, mice were killed; the lung tissue was immediately harvested; and total RNA was isolated. Total cytoplasmic RNA (1 μg) was used for chemokine mRNA analysis by means of the multiprobe RNase protection assay. (C) B6 mice (n = 10 per group) were treated with control PBS, IL-2 (50 000 IU) alone, IL-18 (1 μg) alone, or IL-2 (50 000 IU) plus IL-18 (1 μg) once a day, and 6 hours after the third injection, mice were killed. ELISA assayed the lung tissue supernatants as described in “Materials and methods.” *Significantly (P < .05) higher than in B6 mice treated with control PBS, IL-2 alone, and IL-18 alone.