Activated pDCs and type I IFN in BXD2 mice. A, Images of spleen sections taken from a representative BXD2 mouse and a B6 mouse stained with anti-PDCA1 (pDC, green), MAdCAM-1 (red). B, Representative spleen section from a BXD2 mouse with PNA+ GC (blue) inside follicles demarcated with MAdCAM-1 (red) and surrounded by layers of pDCs (green). C, CpG-A:DOTAP was i.v. injected into BXD2 and B6 mice as described in Materials and Methods. Serum IFN-α levels assayed by ELISA collected at the indicated times (N=3–6, **p<0.01, ***p<0.001 between B6 and BXD2 at the same time point). D, RNA was extracted from peripheral blood cells. Transcripts of Ifna1, Ifna4, Ifna11, and Ifnb isoforms from BXD2 and B6 mice at different age groups were quantitated relative to copy counts of Actin, as described in Materials and Methods (N=6, *p<0.05, **p<0.01, ***p<0.001 noted with BXD2 age groups were compared to BXD2 at the 3–6 months of age, or in the case of B6, **p<0.01, and ***p<0.001 compared to age group-matched BXD2 mice).