Chen Yi-Hsing, Lee Mey-Fann, Tsai Jaw-Ji, Wu Hsin-Ju, Hwang Guang-Yuh
Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung, Taiwan.
Int Arch Allergy Immunol. 2009;150(1):66-74. doi: 10.1159/000210382. Epub 2009 Apr 2.
Forcipomyia taiwana is a tiny blood-sucking midge whose habitat covers large parts of Taiwan and southern China. Female midges bite during the day, causing intense pruritus and swelling in allergic individuals. In this study, we investigated the immune responses of different allergic reactions to midge bites.
F. taiwana (midge)-specific IgE, -IgG and -IgG subclasses were examined by ELISA in 62 human subjects. Peripheral blood mononuclear cells (PBMC) from 6 subjects with solely delayed reactions (SDR) to midge bites and 6 nonallergic controls (NAC) were cultured with midge extract at various time points and assayed. Proliferation of PBMC was measured by MTT assay. Expression of cytokine mRNA was measured by real-time PCR and protein levels by cytometric bead immunoassay or ELISA. Protease activity in midge extract was determined by the Azocoll method.
Midge-specific IgE among subjects with an immediate reaction were significantly elevated compared to SDR and NAC subjects. There were no differences in the level of midge-specific-IgG, -IgG(1), -IgG(2), -IgG(3) and -IgG(4) among subjects with different biting reactions. Midge extract elicited significantly more PBMC proliferation, higher expression of IFN-gamma, IL-10, IL-6 and TNF-alpha in SDR subjects than in NAC. Protease activity was detected in midge extract. Protease inhibitors E64 and pepstatin suppressed midge-extract-induced IL-8 production.
Our results suggest that an immediate reaction to midge bites is IgE-mediated. IFN-gamma, IL-6 and TNF-alpha are involved in delayed reactions to midge bites. A protease-activated pathway may also be involved in the intense, itchy reactions to midge bites.
台湾蠛蠓是一种微小的吸血蠓虫，其栖息地覆盖台湾大部分地区和中国南部。雌性蠓虫在白天叮咬，会使过敏个体产生强烈瘙痒和肿胀。在本研究中，我们调查了对蠓虫叮咬不同过敏反应的免疫应答。
采用酶联免疫吸附测定法（ELISA）检测62名受试者体内台湾蠛蠓特异性IgE、IgG及IgG亚类。在不同时间点，将6名对蠓虫叮咬仅有迟发型反应（SDR）的受试者和6名非过敏对照者（NAC）的外周血单个核细胞（PBMC）与蠓虫提取物共同培养并进行检测。采用MTT法检测PBMC的增殖情况。通过实时聚合酶链反应检测细胞因子mRNA的表达，采用细胞计数珠免疫测定法或ELISA检测蛋白水平。采用偶氮酪蛋白法测定蠓虫提取物中的蛋白酶活性。
速发型反应受试者体内的蠓虫特异性IgE显著高于SDR受试者和NAC受试者。不同叮咬反应受试者的蠓虫特异性IgG、IgG1、IgG2、IgG3和IgG4水平无差异。与NAC相比，蠓虫提取物在SDR受试者中引起的PBMC增殖显著更多，IFN-γ、IL-10、IL-6和TNF-α的表达更高。在蠓虫提取物中检测到蛋白酶活性。蛋白酶抑制剂E64和胃蛋白酶抑制剂可抑制蠓虫提取物诱导的IL-8产生。
我们的结果表明，对蠓虫叮咬的速发型反应是由IgE介导的。IFN-γ、IL-6和TNF-α参与了对蠓虫叮咬的迟发型反应。蛋白酶激活途径可能也参与了对蠓虫叮咬的强烈瘙痒反应。
