C3aR^−/− or C3aRa treated DCs elicit reduced allospecific T-cell responses in vitro. (A-C) Irradiated BM DCs (BALB/c) were cocultured with naive alloreactive CD4 T cells (C57BL/6). T-cell responses were measured by IFN-γ production and/or thymidine uptake. (A) LPS stimulated DCs (ie, C3aR^−/− DCs and their WT control DCs, and C3aRa treated and untreated WT DCs). (B) No LPS stimulated DCs (ie, C3aR^−/− DCs and their WT control DCs, and C3aRa treated and untreated WT DCs). (A-B) Data are shown as mean plus or minus SEM (n = 4, for ELISA; or n = 6, for thymidine uptake). Data were analyzed by Student t test (**P < .006; ***P < .001). A representative of 4 independent experiments is shown. (C) WT DCs treated with different dose of C3aRa (LPS stimulated for 24 hours). (D) Irradiated C3^−/− DCs (C57BL/6) that were treated with or without C3a (LPS stimulated for 24 hours) were cocultured with naive alloreactive CD4 T cells (BALB/c). Untreated WT DCs were included as comparison. (C-D) Data are means plus or minus SEM (n = 4). Data were analyzed by one-way ANOVA. A representative of 2 independent experiments is shown.