The hammock: a reservoir of allergens

INTRODUCTION: Asthma affects approximately 10 percent of the world's population. Sensitization to allergens is an important risk factor, and exposure to allergens is associated with disease severity. METHODS: We performed skin tests to evaluate allergen sensitization to mites, cockroaches, cats, dogs, and molds in 73 asthmatic patients. Enzyme Linked Immunosorbent Assay was used to assay the mite and cockroach allergens found in dust from the bedding, hammocks, bedroom floors, living rooms, and kitchens of 29 patients and 14 controls. RESULTS: Fifty patients (68.5 percent) had positive skin test responses. There were positive responses to D. pteronyssinus (52.0 percent), B. tropicalis (53.4 percent), T. putrescentiae (15.0 percent), E. maynei (12.3 percent), L. destructor (8.2 percent), B. germanica (20.5 percent), P. americana (21.9 percent), Felis catus (10.9 percent), C. herbarium (2.7 percent), A. alternata (4.1 percent), and P. notatun (1.3 percent). The exposure to mite and cockroach allergens was similar in the patients and the controls. The Dermatophagoides pteronyssinus Group 1 levels were highest in the beds and hammocks. The Blattella germanica Group 1 levels were highest in the kitchens, living rooms and hammocks. DISCUSSION: The positive skin tests to mites, cockroaches and cats were consistent with previous studies. D pteronyssinus was the most prevalent home dust mite, and hammocks were a source of allergens. To improve asthma prophylaxis, it is important to determine its association with mite allergen exposure in hammocks.

A revisit to cockroach allergens.

Among cockroaches (CR) that live in people’shomes, two species, i.e., German CR (Blattella germanica) and American CR (Periplaneta americana) predominate in temperate and tropical areas, respectively. CR is an important source of inhalant indoor allergens that sensitize atopic subjects to (localized) type I hypersensitivity or atopy including allergic rhinitis and atopic asthma. In Thailand the predominant CR species is P. americana. CR allergens are found throughout CR infested houses; the number found in kitchens correlates with the degree of CR infestation while sensitization and reactivation of the allergic morbidity are likely to occur in the living room and bedroom. Levels of the CR allergens in homes of CR allergic Thais, measured by using locally made quantification test kits, revealed that the highest levels occur in dust samples collected from the wooden houses of urban slums and in the cool and dry season. CR allergens are proteins that may be derived from any anatomical part of the insect at any developmental stage. The allergens may be also from CR secretions, excretions, body washes or frass. The proteins may be the insect structural proteins, enzymes or hormones. They may exist as dimers/multimers and/or in different isoforms. Exposure to CR allergens in infancy leads to allergic morbidity later in life. Clinical symptoms of CR allergy are usually more severe and prolonged than those caused by other indoor allergens. The mechanisms of acute and chronic airway inflammation and airway hyper-responsiveness (AHR) have been addressed including specific IgE- and non-IgEmediated mechanisms, i.e., role of proteaseactivated receptor-2 (PAR2). Participation of various allergen activated-CD4+ T cells of different sublineages, i.e., Th2, Th17, Th22, Th9, Th25, Tregs/Th3 as well as invariant NKT cells, in asthma pathogenesis have been mentioned. The diagnosis of CR allergy and the allergy intervention by CR population control are also discussed.

Identification of the German Cockroach Allergens in Korean Atopy Using SDS - PAGE and Western Blot Analysis

BACKGROUND: Cockroaches are important components of house dust allergens. In spite of significant subject reactivity to cockroach extracts, the specific source of the allergen remains unclear. OBJECTIVE: This study was performed to identify the important allergens in German cockroach whole body (GWBE), egg (GEE) and fecal (GFE) extracts in Korean atopy, and to compare the reactivity of GWBE and GEE by Western blot inhibition. METHODS: Sera from 11 subjects with Korean atopy were used for sodium dodecil sulfate polyacrylamide gel elctrophoresis (SDS-PAGE) and Western blot analysis. RESULTS: Allergenic fractions in German cockroach extracts were numerous and distributed throughout the wide range of molecular weights. The important allergens of GWBE, GFE and GEE were similar to each other by using SDS-PAGE and Western blot ysis. The aUergen bands at 55 kd showed the most significant reactivity; in GWBE, GFE and GEE 73%, 82%, 55%, respectively. Other bands exhibiting significant activity were the 67 kd band with 37%, 19% and 19%, the 64 kd band with 64%, 37% and 9% respectively. Furthermore, Western blot inhibition investigations revealed that either GWBE or GEE could almost completely inhibit the reactivity of the other extract. CONCLUSION: This study confirms that the 55 kd allergen can be considered as the major allergen in Korean atopy and demonstrated that the GWBE and GEE antigens have identical IgE-binding sites.