IC-induced modulation of FcγR mRNAs is impaired in C5aR^–/– mice. mRNA expression of C5aR and FcγRs was assessed in BAL-AM cells from the indicated mice obtained 2 hours after OVA/anti-OVA challenge (IC). Mice not receiving the OVA antigen served as Ab controls (Ab). mRNA analysis by TaqMan RT-PCR showed significantly increased FcγRIII (upper left panel) and FcRγ (upper right panel) versus reduced FcγRII (lower left panel) mRNA levels in C57BL/6 (WT) mice, but not C5aR^–/– mice, in response to IC treatment. C5aR mRNA expression do not differ between Ab and IC treatment groups of C57BL/6 WT and FcγRIII^–/– mice. Data are represented as means ± SEM (n = 5–6 mice in each group, *P < 0.05).