Effect of IL-18 on serum levels of IFN-γ in the BM transplant recipients.

(A) B6 Ly5.2 (CD45.1⁺) animals were irradiated and received BM transplants from BALB/c donor mice that had been injected with control diluent (▪) or IL-18 (░) as in Figure 1. Serum was obtained (n = 3 mice/group) by retro-orbital venous puncture on day 4 after BMT; serum levels of IFN-γ were significantly reduced in recipients of IL-18–treated (░) versus diluent-treated (▪) donors; *P < .05. Results from 1 of 3 similar experiments are shown. (B) B6 animals were irradiated and received transplants of cells from either syngeneic B6 (H2^b) donors (■) or allogeneic STAT6-deficient (H2^d) donor mice injected with control diluent (▪) or IL-18 (░) for 10 days as in Figure 1. Serum was obtained (n = 4/group) on day 4 after BMT and analyzed for cytokines. IFN-γ was increased in the recipients of IL-18–treated (░) and control-treated (▪) allogeneic donor cells (▪ vs ░;P = NS). IL-4 was not detected. Error bars represent standard error.