Analysis of C1q production in monocyteand CD34⁺-derived DCs and macrophages. Day-7 immDCs and macrophages were lysed for mRNA extraction (A) or analyzed using FACS (B). For RT-PCR analysis, specific primers for the C1q A chain were used. While histograms indicate isotype control. (C) Detection of C1q purified from serum using a sandwich ELISA. (D) Day-7 macrophages and immDCs were generated from the same monocyte population of 7 independent donors, and C1q production was analyzed in duplicate in 48-hour culture supernatants. Each line represents the mean C1q production in the 2 cell types of 1 donor. The difference between macrophages and DCs was statistically significant (P = .0035, paired Student t test). (E) Freshly isolated CD34⁺ cord blood hematopoietic progenitors were cultured for 6 days and then FACS-sorted into CD1a⁺CD14^– and CD1a^–CD14⁺ cells. Sorted cells were then cultured independently for 48 hours. Supernatants were collected (day 8) and used in C1q-specific ELISA. Alternatively, sorted cells were cultured until day 13. At day 13, cells were harvested and then cultured for 48 hours. Supernatants were collected (day 15) and used in C1q-specific ELISA. Results are shown as mean ± SD of an experiment performed in triplicate. Similar results were obtained in 2 different donors. *P < .0001 compared with Langerhans cells; 2-way ANOVA of 2 experiments.