ABSTRACTInfection with gastrointestinal helminths generates a dominant type 2 response among both adaptive (Th2) and innate (macrophage, eosinophil, and innate lymphoid) immune cell types. Two additional innate cell types, CD11chighdendritic cells (DCs) and basophils, have been implicated in the genesis of type 2 immunity. Investigating the type 2 response to intestinal nematode parasites, includingHeligmosomoides polygyrusandNippostrongylus brasiliensis, we first confirmed the requirement for DCs in stimulating Th2 adaptive immunity against these helminths through depletion of CD11chighcells by administration of diphtheria toxin to CD11c.DOG mice. In contrast, responsiveness was intact in mice depleted of basophils by antibody treatment. Th2 responses can be induced by adoptive transfer of DCs, but not basophils, exposed to soluble excretory-secretory products from these helminths. However, innate type 2 responses arose equally strongly in the presence or absence of CD11chighcells or basophils; thus, in CD11c.DOG mice, the alternative activation of macrophages, as measured by expression of arginase-1, RELM-α, and Ym-1 (Chi3L3) in the intestine followingH. polygyrusinfection or in the lung followingN. brasiliensisinfection, was unaltered by depletion of CD11c-expressing DCs and alveolar macrophages or by antibody-mediated basophil depletion. Similarly, goblet cell-associated RELM-β in lung and intestinal tissues, lung eosinophilia, and expansion of innate lymphoid (“nuocyte”) populations all proceeded irrespective of depletion of CD11chighcells or basophils. Thus, while CD11chighDCs initiate helminth-specific adaptive immunity, innate type 2 cells are able to mount an autonomous response to the challenge of parasite infection.
Gastrointestinal Helminths of the Marshland Frog, Fejervarya limnocharis (Anura: Ranidae), from Taiwan, R.O.C
