Hellberg W, Wilson A D, Mellor P, Doherr M G, Torsteinsdottir S, Zurbriggen A, Jungi T, Marti E
Division of Clinical Research, Department of Clinical Veterinary Medicine, University of Berne, Bremgartenstr. 109 A, P.O. Box, 3001 Berne, Switzerland.
Vet Immunol Immunopathol. 2006 Sep 15;113(1-2):99-112. doi: 10.1016/j.vetimm.2006.04.009. Epub 2006 Jun 23.
Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by IgE-mediated reactions to bites of Culicoides and sometimes Simulium spp. The allergens causing IBH are probably salivary gland proteins from these insects, but they have not yet been identified. The aim of our study was to identify the number and molecular weight of salivary gland extract (SGE) proteins derived from Culicoides nubeculosus which are able to bind IgE antibodies (ab) from the sera of IBH-affected horses. Additionally, we sought to investigate the IgG subclass (IgGa, IgGb and IgGT) reactivity to these proteins. Individual IgE and IgG subclass responses to proteins of C. nubeculosus SGE were evaluated by immunoblot in 42 IBH-affected and 26 healthy horses belonging to different groups (Icelandic horses born in Iceland, Icelandic horses and horses from different breeds born in mainland Europe). Additionally, the specific antibody response was studied before exposure to bites of Culicoides spp. and over a period of 3 years in a cohort of 10 Icelandic horses born in Iceland and imported to Switzerland. Ten IgE-binding protein bands with approximate molecular weights of 75, 66, 52, 48, 47, 32, 22/21, 19, 15, 13/12 kDa were found in the SGE. Five of these bands bound IgE from 50% or more of the horse sera. Thirty-nine of the 42 IBH-affected horses but only 2 of the 26 healthy horses showed IgE-binding to the SGE (p<0.000001). Similarly, more IBH-affected than healthy horses had IgGa ab binding to the Culicoides SGE (19/22 and 9/22, respectively, p<0.01). Sera of IBH-affected horses contained IgE, IgGa and IgGT but not IgGb ab against significantly more protein bands than the sera of the healthy horses. The cohort of 10 Icelandic horses confirmed these results and showed that Culicoides SGE specific IgE correlates with onset of IBH. IBH-affected horses that were born in Iceland had IgGa and IgGT ab (p< or =0.01) as well as IgE ab (p=0.06) against a significantly higher number of SGE proteins than IBH-affected horses born in mainland Europe. The present study shows that Culicoides SGE contains at least 10 potential allergens for IBH and that IBH-affected horses show a large variety of IgE-binding patterns in immunoblots. These findings are important for the future development of a specific immunotherapy with recombinant salivary gland allergens.
昆虫叮咬超敏反应（IBH）是马匹的一种过敏性皮炎，由对库蠓叮咬的IgE介导反应引起，有时也涉及蚋属昆虫。引发IBH的过敏原可能是这些昆虫的唾液腺蛋白，但尚未得到鉴定。我们研究的目的是确定源自朦胧库蠓的唾液腺提取物（SGE）中能够结合受IBH影响马匹血清中IgE抗体（ab）的蛋白质数量和分子量。此外，我们还试图研究这些蛋白质与IgG亚类（IgGa、IgGb和IgGT）的反应性。通过免疫印迹法评估了42匹受IBH影响和26匹健康马匹（属于不同组，包括出生在冰岛的冰岛马、冰岛马以及出生在欧洲大陆的不同品种马匹）对朦胧库蠓SGE蛋白质的个体IgE和IgG亚类反应。此外，还在一组10匹出生在冰岛并进口到瑞士的冰岛马中，研究了在暴露于库蠓叮咬之前以及3年期间的特异性抗体反应。在SGE中发现了10条IgE结合蛋白带，其近似分子量分别为75、66、52、48、47、32、22/21、19、15、13/12 kDa。其中5条带结合了50%或更多马匹血清中的IgE。42匹受IBH影响的马匹中有39匹，但26匹健康马匹中只有2匹显示出与SGE的IgE结合（p<0.000001）。同样，受IBH影响的马匹中IgGa ab与库蠓SGE结合的数量多于健康马匹（分别为19/22和9/22，p<0.01）。受IBH影响的马匹血清中含有的针对显著更多蛋白带的IgE、IgGa和IgGT，但不含IgGb ab，比健康马匹血清中的多。这组10匹冰岛马证实了这些结果，并表明库蠓SGE特异性IgE与IBH的发作相关。出生在冰岛的受IBH影响的马匹针对SGE蛋白的IgGa和IgGT ab（p≤0.01）以及IgE ab（p = 0.06）数量显著高于出生在欧洲大陆的受IBH影响的马匹。本研究表明，库蠓SGE至少含有10种IBH潜在过敏原，且受IBH影响的马匹在免疫印迹中显示出多种IgE结合模式。这些发现对于未来开发重组唾液腺过敏原特异性免疫疗法具有重要意义。
