Figure 3. Limited activation and function of pDCs in LCMV-infected 2-week-old mice.

(A) Percentages of infant and adult splenic CD11c^intSiglec-H⁺B220⁺PDCA-1⁺ pDCs determined by FACS staining before (naive) and 1 day after LCMV-WE infection (LCMV). One of three representative experiments is shown. *, p<0.05. (B) Fold increase of CD80, CD40 and CD86 expression by infant and adult splenic pDCs, determined by FACS staining between day 0 and day 1 after LCMV-WE infection. *, p<0.05. n = 6 to 8 mice per group. One of two representative experiments is shown. (C) Expression of IFN-α, and IRF-7 mRNAs in sorted pDCs from infant or adult spleens before (naive) and 1 day after LCMV-WE infection (LCMV). *, p<0.05. n = 4 pools of 2 adult mice or 3 pools of 6 to 8 infant mice. One of two representative experiments is shown. (D) Pictures of isolated pDCs from infected infant and adult mice after cytospin, methanol fixation and IRF-7 (green) and DAPI (blue) staining (EC Plan Neofluar 40x 1.3 Oil DIC objective, Zeiss LSM510 Meta confocal microscope). Upper and lower panels showing non-translocated and translocated nuclear IRF-7, respectively. (E) Percentage of IRF-7⁺ pDCs displaying IRF-7 translocation into the nucleus. *, p<0.05. More than 1000 IRF7⁺ pDCs (from at least 4 different individual adult or 4 different pools of 6 to 8 infant mice) were counted. One of two representative experiments is shown.