Actions of Allergens and Mediators in Allergy

It has long been recognized that allergic inflammation is the fundamental pathological changes of allergy. Soluble aller-gens, specific IgE (sIgE), and mast cells or basophils are three key factors of allergy, representing causative factors, messenger , and primary effector cells, respectively. Eosinophils and neutrophils are known as secondary effector cells. In recent years, varieties of novel allergens and molecules involved in the allergic inflammation have been discovered, which makes the current understanding of the mechanisms of allergy even more confusing. We still have long way to go before the clear picture of pathogenesis of allergic inflammation can be accomplished, but our continuous and hard effort will help us to finally reach our destination drawing a complete picture of allergy. In this respect, this special issue will add a few new points in the picture of allergic inflammation. Cockroach allergy has been associated with the development of asthma and recognized as a risk factor for emergency room admission of asthmatic patients, especially among inner city children living in low-income houses infested with cockroaches [1]. In the special issue, American cockroach allergen Per a 5 has been recognized as a minor allergen for American cockroach. Since its secondary protein structure is obtained and recombinant Per a 5 is generated, it will be a useful tool for studying the role of Per a 5 in cockroach allergy. Moreover, it is discovered that aryl hydrocarbon receptor (AhR) expression is higher in airway fibroblasts from asthmatic subjects, particularly when fibroblasts are treated with cockroach extract. An AhR agonist, 2,3,7,8-tetrachlorodibenzo-p-dioxin, can significantly enhance cockroach extract induced TGFí µí»½1 production in fibroblasts. These results suggest the role of AhR in modulating cockroach allergen induced immune responses through controlling the active TGFí µí»½1 release. Classification of allergens in food plants and pollens is never easy. By using sequence alignment, progressive clustering, and comparison of 3-dimensional structures, Y. He and colleagues classify major allergens into 21 representative allergen groups, which are further divided into seven structural classes, each of which contains similar structural components. The grouping of allergens may help to understand the cross-reactivity between allergens. Unlike studies on eosinophils and neutrophils alone, the interactions between these two secondary effector cells of allergy are relatively less investigated. Since it is an essential issue for understanding pathogenesis of allergic inflammation , it is examined by R. A. Luz and colleagues. Significant recruitment of eosinophils, neutrophils, and mono-cytes/macrophage by eotaxin is …