Clinico-immunochemical studies on airborne Areca catechu L. Pollen, a probable risk factor in emergency asthma hospitalization from Eastern India.

BACKGROUND: The pollen grain of the Areca catechu L. tree is airborne and allergenic. This study aimed to know the role of this pollen as a source of aeroallergen with effect on emergency asthma hospitalization, to isolate its important allergic fraction and to check its cross-reaction with betel nut. METHODS: Areca pollen was monitored with a Burkard sampler. Determination of allergenic activities was studied by in vivo and in vitro analyses. Asthma hospitalization data were collected from two nearby hospitals. The pollen extract was fractionated by a combination of DEAE-Sephadex and Sephacryl S-200 column. The protein components were observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cross-reactivity of Areca pollen and betel nut was shown by IgE enzyme-linked immunosorbent assay (ELISA) inhibition. RESULTS: The Areca pollen was perennially airborne. Skin test results of respiratory allergic patients showed 38.6% positivity. The detected aeroallergen spots in particle immunoblotting correlated significantly with airborne pollen count. Areca pollen showed a significant positive correlation with asthma hospitalization. There are 6 IgE-reactive protein components in the whole-pollen extract. IgE-reactive fraction 1 was resolved into 4 subfractions. Subfraction 1a showing IgE reactivity contained 3 protein components, among which 2 of 48 and 118 kDa were IgE reactive. The 48-kDa component was reported to be cross-reactive with other palm pollen types. In IgE ELISA inhibition, the betel nut extract showed 50% inhibition with about 110 ng/ml concentration. CONCLUSION: A. catechu pollen is a significant contributor to the aeroallergen load in India. Its partially purified IgE-reactive fraction may be useful in therapeutics. The betel nut extract showed remarkable cross-reactivity with Areca pollen.

Clinical and immunobiochemical characterization of airborne Delonix regia (Gulmohar tree) pollen and cross-reactivity studies with Peltophorum pterocarpum pollen: 2 dominant avenue trees from eastern India.

BACKGROUND: Delonix regia and Peltophorum pterocarpum pollen are important aeroallergens for type 1 hypersensitivity in the tropics. The IgE-binding proteins of D regia and their cross-allergenity with P pterocarpum pollen have not been evaluated. OBJECTIVES: To isolate and characterize the IgE-binding proteins of D regia pollen for the first time and to investigate the cross-allergenity with P pterocarpum pollen belonging to the same family (Leguminosae). METHODS: Allergenic activities were determined by in vivo and in vitro analyses. Pollen extract was fractionated by a combination of 2 columns (diethyl amino ethyl Sephadex and Sephacryl S-200). Protein components were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, periodic acid-Schiff staining, and immunoblotting. In vitro inhibition tests were performed to evaluate the cross-reactivity. RESULTS: The skin prick test results of the patients with respiratory allergies in Calcutta, India, showed 31.1% positivity with D regia pollen. Nine IgE-reactive protein components were found in the crude extract. An optimum IgE-reactive fraction was resolved into 4 subfractions. Subfraction A, which showed maximum IgE reactivity, contained 2 (96- and 66-kDa) IgE-reactive protein components. The 66-kDa component was found to be glycoprotein. Remarkable cross-reactivity between D regia and P pterocarpum pollen was found on IgE enzyme-linked immunosorbent assay inhibition and dot blotting. Shared IgE-binding components (66, 56, 32, 28, 25, and 23 kDa) were observed between D regia and P pterocarpum pollen extracts, whereas the 96- and 43-kDa components were specific to D regia. CONCLUSION: The purification of the IgE-binding proteins and the identification of the shared/cross-reactive proteins in these taxonomically related pollen members should be helpful for the diagnosis and therapy of patients susceptible to these pollens.