C3a treatment enhances the capacity of DCs for Ag uptake and cell activation as well as their function in Ag presentation. C3a (20 nM or the indicated concentration) was added into DC culture medium every 2 days from the beginning of BM cell culture. (A) Ag uptake performed in 6-day DCs. Data are shown as mean plus or minus SEM (n = 4). Data were analyzed by Student t test. (B) Surface expression of MHC class II (MHC-II), CD40, and B7.2 analyzed in 7-day DCs by flow cytometry. Data are shown as mean plus or minus SEM (n = 2). (C) Ag presentation performed in 6-day DCs. Data are shown as mean plus or minus SEM (n = 4 for ELISA; n = 8 for thymidine uptake). (D) Six-day DCs were further cultured for 24 hours in the presence or absence of LPS (0.5 μg/mL) as well as C3a; and the supernatants were used for cytokine measurement. Data are shown as mean plus or minus SEM (n = 4). Data were analyzed by Student t test. ***P < .001; **P < .005; *P < .05; NS, no significant difference. A representative of 3 independent experiments for all figures is shown.