A Recombinant Fragment of Human Surfactant Protein D Suppresses Basophil Activation, Th2 and B Cell Responses in Grass Pollen-induced Allergic Inflammation

Rationale: Recombinant fragment of human surfactant protein D (rfhSP-D) has been shown to suppress house dust mite– and Aspergillus fumigatus–induced allergic inflammation in murine models.Objectives: We sought to elucidate the effect of rfhSP-D on high-affinity IgE receptor– and CD23-mediated, grass pollen–induced allergic inflammatory responses.Methods: rfhSP-D, containing homotrimeric neck and lectin domains, was expressed in Escherichia coli BL21(λDE3)pLysS cells. Peripheral blood mononuclear cells and sera were obtained from individuals with grass pollen allergy (n = 27). The effect of rfhSP-D on basophil activation and histamine release was measured by flow cytometry. IgE-facilitated allergen binding and presentation were assessed by flow cytometry. T-helper cell type 2 (Th2) cytokines were measured in cell culture supernatants. The effect of rfhSP-D on IgE production by B cells when stimulated with CD40L, IL-4, and IL-21 was also determined.Measurements and Main Results: rfhSP-D bound to Phleum pra...