IFN-γ mRNA expression in macrophages of RAG2^-/-γ_c^-/- mice and in purified CD11b⁺F4/80⁺ BMMΦs and CD4⁺ T cells of C57BL/6 and BALB/c mice. (A) Resident PCs, PECs, and BMMΦs of RAG2^-/-γ_c^-/- mice were incubated with IL-12 (with or without IL-18), IL-18, or LPS (1 μg/mL) for 24 hours, and RNA was prepared and analyzed by conventional RT-PCR for hypoxanthine-guanine phosphoribosyltransferase (HPRT) and IFN-γ. Representative of 3 experiments. (B) Sorted CD11b⁺F4/80⁺ BMMΦs and CD4⁺ purified T cells of naive mice were stimulated with IL-12/IL-18 and harvested for real-time RT-PCR analysis at 24 hours. IFN-γ mRNA transcription was calculated by calibrating to unstimulated C57BL/6 BMMΦs. The data represent the mean (± SEM) of 2 experiments with C57BL/6 BMMΦs and T cells (▪) and the results of one experiment with BALB/c BMMΦs and T cells (▦).