Cross-reactive IgE-binding Proteins from Philippine Allergenic Weeds and Trees Pollen Extracts

Abstract

Background. The Philippines has a wide variety of plant species with potential to produce allergenic pollen grains. Most of the study subjects which are residents in Manila tested positive to Fabaceae and Amaranthaceae. Weeds, especially the Amaranthaceae and Fabaceae families, are relevant triggers of allergy as they are highly adaptive and can grow despite adverse weather conditions. However, only a few allergens have been identified among these families and listed in the International Union of Immunological Societies allergen nomenclature database. Currently, local pollen grains are being processed at the Medical Research Laboratory of our institution to produce crude pollen extracts for use in specific diagnostic skin tests and in subcutaneous immunotherapy of patients with respiratory allergies all over the country. However, these extracts have not been characterized and data of cross-reactivity is limited. 

Objectives. This study aimed to evaluate the IgE binding activity of allergen extracts from Philippine weeds and trees, and determine their cross-reactive components.

Methods. Pollen extracts from Amaranthus spinosus (pigweed), Mimosa pudica (makahiya), Tridax procumbens (wild daisy), Albizia saman (acacia), Leucaena leucocephala (ipil-ipil), Mangifera indica (mango), and Cocos nucifera (coconut) were extracted and analyzed for crossreactivity using ELISA and Western blot. 

Results. Cross-reaction was observed between ipil-ipil and coconut, and between makahiya and wild daisy. IgE bound to protein components at ~20, 18, and 15 kDa of the weeds, while for the trees, IgE bound to protein components at ~35 and ~15 kDa which may be responsible for the cross-inhibitions observed. 

Conclusion. Data may contribute to the development of immunotherapeutic strategies and diagnostic applications for respiratory allergies, comprising the production of standardized panel of allergens thus eliminating unwanted side effects and providing patients with safer diagnosis and therapy.