Lung surfactant protein D (SP-D) is a hydrophilic soluble pattern recognition innate immune molecule involved in the clearance of pathogens, apoptotic/necrotic cells, and down-regulation of allergic inflammation. The fragment of SP-D has been shown to be involved in pattern recognition of glycoprotein allergens and inhibit histamine release by sensitised basophils in vitro in response to house dust mite (Dermatophagoides pteronyssinus) and Aspergillus fumigatus allergens. Studies have shown that the therapeutic application of SP-D caused a marked reduction in specific IgE and IgG1 levels, along with peripheral blood eosinophilia and pulmonary infiltration in BALB/c murine model of allergic bronchopulmonary aspergillosis (ABPA). The effect of SP-D on allergic effector cell and allergen induced T, B cell responses are yet to be evaluated in humans. The overall aim of this study is to determine effect of SP-D on grass pollen allergen induced basophil activation and histamine release. Furthermore, we will investigate whether SP-D inhibits CD23-mediated facilitated allergen presentation (FAP) by B cell to CD4+ (Th2) cells and Th2 cytokine responses in subjects with seasonal allergic rhinitis.
An allergic reaction is triggered when the cells in the lungs come in contact with allergens. Allergens interact with cells called basophils and these cells release chemicals, including histamine, that trigger the allergic reaction. A protein called surfactant protein D is released upon exposure to allergen and plays a part in the first line of defence against foreign particles by inhibiting this interaction. The overall aim of this study is to investigate the effect of SP-D on basophil-allergen interaction in patients with seasonal allergic rhinitis and in healthy individuals. In additionally, the effects of SP-D will be tested on T and B lymphocytes that cause allergic reaction.