FIGURE 6.

MDA- and PC-inhibitable Abs to apoptotic cells recruit C1q and enhance phagocytosis by DCs. A, Representative studies of IgM and C1q binding to ACs after incubation with 10% sera from naive or AC-treated wild-type adult mice or mice deficient in the V_HS107.1 gene (B6.S107.1^−/−). The percentage of DCs that ingested ACs is indicated, after incubation for 1 h at 37°C. B, Results from replicate immature DC cultures, after incubation for 1 h at 37°C, showed consistent direct correlations of the proportion of added sera with the resulting level of enhanced AC apoptosis in replicate cultures. Such differences were consistently documented in comparisons of replicate cultures containing different proportions of sera. C, To determine the Ag specificity of serum Abs that affect DC phagocytosis, sera were first preincubated with PC-BSA, MDA-BSA, or BSA at 50 μg/ml for 1 h at 37°C before addition to cultures for 1 h at 37°C. Bars represent mean values and SDs for triplicate cultures. Top horizontal line is the mean level after serum incubation with BSA, while the bottom horizontal line is the mean level obtained with Ig-deficient sera (i.e., Ig-independent activity level). Results are representative of three independent studies.