Administration of IL-18 in combination with IL-12 is lethal in C57BL/6 and SCID mice.

(A) Four- to 6-week-old female C57BL/6 mice were injected daily IP with rmuIL-18 (0.1 or 0.5 μg/d) plus rmuIL-12 (1 μg/d) and monitored for toxicity. No deaths were observed in mice receiving IL-18 or IL-12 alone (not shown). (B) Four- to 6-week-old female C.B-17 SCID mice were injected daily IP with IL-18 (0.5 μg/d) plus IL-12 (1 μg/d), or IL-18 alone and monitored for toxicity. These results are representative of 4 separate experiments.