CD4 and infection: Lastly, as in CD301b+ DC-depleted mice13, the CD301bΔMHCII mice had similar numbers of CD44+ activated CD4+ T cells but showed impaired IL-4 production from the activated CD4+ T cells in the skin- and lung-dLNs upon subcutaneous infection with Nb, a model in which the parasites quickly migrate from the skin to the lung within one day, indicating the requirement of cognate interaction with CD301b+ DC for the parasite-induced Th2 cell differentiation in the endogenous polyclonal CD4+ T cells (Fig. 1l–n).