Effect of apoptotic cells on DC cytokine gene transcription and secretion.

(A) Comparative RPA analysis of cytokine mRNA transcribed by DCs following phagocytosis of apoptotic splenocytes. mRNA was isolated from immunomagnetic bead-sorted BM DCs after coincubation with apoptotic cells for 4 or 16 hours, in the absence or presence of 200 μg/mL LPS. For most cytokines, the changes in mRNA levels were evident after 16 hours with the exception of IL-6. (B) Quantitative analysis of mRNA cytokine gene expression. Densitometry analysis of each lane was performed on scanned autoradiographs, and all values are expressed relative to corresponding housekeeping gene transcripts (L32). Densitometric values were pooled from 3 separate experiments; *P ≤ .05; **P ≤  .01; ***P ≤ .001. (C) Quantitation by ELISA of cytokines secreted by DCs after phagocytosis of apoptotic splenocytes in the presence or absence of 200 μg/mL LPS. Basal levels of TGF-β1 in the culture medium were deducted. Data are displayed as the means ± SDs of 3 different experiments.