Increased activation of cells in the immature and mature pDC subsets of older bicongenic mice.

<p>Expression of the activation markers (A) B7.2 and MHCII was quantified by mean fluorescent intensity (MFI) on splenic pDC gated as CD11c+ B220+ CD11b− in 8 week old (young; Yng) and 8 month old (Old) B6 and bicongenic mice. pDC populations were further characterized with additional surface markers to remove contaminating IgM+ CD19+ ABCs and to determine the maturity of pDC. Immature (CD9+ SiglecH−) and mature (SiglecH+ CD9−) pDC were gated on the CD11c+ B220+ CD11b− IgM− CD19− splenic pDC population and the data expressed as a proportion of total live splenocytes (B) and as a proportion of total pDC (C). (D) PDCA-1 was highly expressed on mature (SiglecH+ CD9−) but not immature (CD9+ SiglecH−) pDC subsets. Elevated expression of activation markers (E) B7.2 and (F) MHCII was seen in older bicongenic mice in both pDC subsets gated from the CD11c+ B220+ cell population. Representative histogram plots for older B6 (grey dotted line) and bicongenic mice (solid black line) for (G) B7.2 and (H) MHCII were gated on the CD11c+ B220+ CD11b− cells population excluding ABCs, in both the CD9+SiglecH− and SiglecH+CD9− populations. Results from this figure show representative data from one of three independent experiments. The p values for significant differences between B6 and bicongenic mice are shown, *p<0.05.