Genomic DNA released by dying cells induces the maturation of APCs

Mature APCs play a key role in the induction of Ag-specific immunity. This work examines whether genomic DNA released by dying cells provides a stimul us for APC maturation. Double-stranded but not single-stranded genomic DNA triggered APC to up-regulate expression of MHC class I/II and various costi mulatory molecules. Functionally, dsDNA enhanced APC function in vitro and improved primary cellular and Immoral immune responses in vivo. These effec ts were dependent on the length and concentration of the dsDNA but were ind ependent of nucleotide sequence. The maturation of APC induced by dsDNA may promote host survival by improving immune surveillance at sites of tissue injury/infection.