Clinical and immunobiochemical characterization of airborne Peltophorum pterocarpum (yellow gulmohar tree) pollen: a dominant avenue tree of India

Abstract

Background: Peltophorum pterocarpum (yellow gulmohar, PP) pollen is an important aeroallergen for type I hypersensitivity in the tropics.

Objective: To isolate and characterize the IgE-binding proteins of PP pollen for the first time.

Methods: Pollen extract was fractionated by a combination of Sephacryl S-200 column and diethylaminoethyl-Sephadex column. Allergen characterization was done by sodium dodecyl sulphate polyacrylamide gel electrophoresis, periodic acid-Schiff staining, enzyme-linked immunosorbent assay, and western blotting. Allergenic activities were determined by in vivo (skin prick test) and in vitro (enzyme-linked immunosorbent assay and histamine release) analyses. To determine whether the carbohydrate chains are involved in immunoreactivity, deglycosylation of PP pollen proteins was performed.

Results: SPT results on the respiratory allergic patients of Calcutta showed that 32.77% showed positivity with PP pollen. Eight IgE-reactive protein components were found in crude extract. Optimum IgE-reactive fraction I was resolved into five subfractions. The subfraction la showed maximum IgE reactivity containing the 28 kDa IgE-reactive component. Periodate oxidation showed that protein component was involved in its IgE binding. Twenty-eight kilodalton IgE reactive protein component was recognized by 75% of PP-sensitive patients in Western blotting. It also induced significant histamine release in sensitive patient sera.

Conclusions: The purified 28 kDa protein is a clinically relevant allergen with a potential for diagnosis and therapy of patients susceptible to PP pollen. Ann Allergy Asthma Immunol. 2011;106:412-420.