Alpha-Actinin Is a New Type of House Dust Mite Allergen

Main indoor allergens for humans are from house dust mites. There are more than 30 allergens in Dermatophagoides farinae but only fourteen allergens have been identified from this mite including Der f 1–3, 6, 7, 10, 11, 13–18, and 22. A native allergen protein (Der f 24, 90 kDa) was purified from D. farinae by gel filtration and anionic exchange liquid chromatography combined with IgE immunodetection. Its primary structure was determined by Edman degradation, mass spectrometry analysis and cDNA cloning. Enzyme-linked immunosorbent assay inhibition tests (ELISA-IT), immunoblots, basophil activation test (BAT) and skin prick test (SPT) were performed to evaluate the allergenicity. It was identified as an alpha (α)-actinin containing a CaM-like domain with EF-hand motifs. Der f 24 reacted to sera from 85.4% (35/41) of patients on western blot analysis. It reduced ∼20% sera IgE reactivity to D. farinae extracts on a competitive ELISA. Eighty percent (8/10) of patients with D. farinae allergy showed positive reactions to Der f 24 in skin prick test. The expression of CD63 on basophils from patients was up-regulated by Der f 24 by ∼5.4-fold. Alpha-actinin was identified as a new type of house dust mite allergen. To the best of our knowledge, this is the first report of α-actinin as an allergen.

人类主要的室内变应原来源于屋尘螨。粉尘螨（Dermatophagoides farinae）中存在超过30种变应原，目前仅从中鉴定出14种，分别为Der f 1~3、6、7、10、11、13~18及22。研究人员通过凝胶过滤结合阴离子交换液相色谱法，并联合IgE免疫检测，从粉尘螨中纯化得到一种天然变应原蛋白（Der f 24，分子量90 kDa）。通过埃德曼降解、质谱分析及cDNA克隆技术确定了该蛋白的一级结构。采用酶联免疫吸附试验抑制试验（Enzyme-linked immunosorbent assay inhibition tests, ELISA-IT）、免疫印迹、嗜碱性粒细胞活化试验（basophil activation test, BAT）与皮肤点刺试验（skin prick test, SPT）对其变应原性进行评估。该蛋白被鉴定为一种含有钙调蛋白样结构域且带有EF手性基序的α-辅肌动蛋白。免疫印迹分析显示，Der f 24可与85.4%（35/41）的过敏患者血清发生反应。竞争性酶联免疫吸附试验结果表明，Der f 24可使患者血清针对粉尘螨提取物的IgE反应性降低约20%。80%（8/10）的粉尘螨过敏患者在皮肤点刺试验中对Der f 24呈阳性反应。Der f 24可使患者嗜碱性粒细胞表面CD63的表达水平上调约5.4倍。α-辅肌动蛋白被确定为一类新型屋尘螨变应原。据我们所知，本研究首次报道α-辅肌动蛋白作为一种变应原。