pDCs express Spi-B at the protein level.

Western blot analysis of Spi-B protein from pDCs. Cytoplasmic or nuclear protein extracts were prepared from pDCs as indicated in “Materials and methods.” The extracts were separated by SDS-PAGE and analyzed by Western blotting using preimmune sera (pI) and anti–Spi-B sera (I). Blots were visualized by chemoluminescence. The size of molecular mass standard is indicated on the right. Tonsillar B cells were used as positive controls.