Surfactant Protein-D Is Essential for Immunity to Helminth Infection

Pulmonary epithelial cell responses can enhance type 2 immunity and contribute to control of nematode infections. an important epithelial product is the collectin surfactant protein d (sp-d). we found that sp-d concentrations increased in the lung following nippostrongylus brasiliensis infection; this increase was dependent on key components of the type 2 immune response. we carried out loss and gain of function studies of sp-d to establish if sp-d was required for optimal immunity to the parasite. n. brasiliensis infection of sp-d-/- mice resulted in profound impairment of host innate immunity and ability to resolve infection. raising pulmonary sp-d levels prior to infection enhanced parasite expulsion and type 2 immune responses,including increased numbers of il-13 producing type 2 innate lymphoid cells (ilc2),elevated expression of markers of alternative activation by alveolar macrophages (alvm) and increased production of the type 2 cytokines il-4 and il-13. adoptive transfer of alvm from sp-d-treated parasite infected mice into naïve recipients enhanced immunity to n. brasiliensis. protection was associated with selective binding by the sp-d carbohydrate recognition domain (crd) to l4 parasites to enhance their killing by alvm. these findings are the first demonstration that the collectin sp-d is an essential component of host innate immunity to helminths. © 2016 thawer et al.