RT-PCR of spleen cells 24 hours p.i. showed that mRNA expression of IFN-b and total IFN-a were not altered regardless of pDC depletion (Fig. 4B) . Similarly, serum levels of these cytokines did not reveal any significant differences between mice depleted of pDCs or control mice (Fig. 4C) . Moreover, bacterial loads in spleens and livers of such mice were also similar (Fig. 4C) . Hence, we conclude that pDCs do not significantly contribute to type I IFN production and also do not have a physiological relevance with regard to colonization of spleen and liver during murine listeriosis.