BACKGROUND

Allergic respiratory diseases are prevalent in the Philippines, with allergic rhinitis and asthma occurring at 20% and 8.7% of the population, respectively. The diagnosis of respiratory allergies is achieved by a combination of patient history and different screening tools, especially for the identificati on of the allergic triggers such as allergy skin prick test (SPT) and serum-specific IgE enzyme-linked immunosorbent assays (sIgE ELISA). The Philippines, being a tropical country, have a wide variety of plant species with potential to produce allergenic pollen grains. Knowledge of the sensitization profiles of Filipino allergic patients to our local pollen allergens is currently limited.

OBJECTIVES

The aim of this study is to determine the sensitization profile of patients with respiratory allergies (allergic rhinitis and/or asthma) through the allergy skin prick test (SPT) using allergenic local pollen extracts. It also aimed to determine if there is a positive agreement between the SPT and sIgE ELISA positivity rate and whether the results have relationship with the pollen purity and the protein content of the extracts.

METHODS

Pollen allergens were extracted from Amaranthus spinosus (pigweed), Mimosa pudica (makahiya), Tridax procumbens (wild daisy), Imperata cylindrica (cogon), Oryza sativa (rice), Pennisetum polystachion (foxtail grass), Sorghum halepense (Johnson grass), Albizia saman (acacia), Cocos nucifera (coconut), Leucaena leucocephala (ipil-ipil), and Mangifera indica (mango). SPT was performed at the Allergy Clinic of the University of the Philippines-Philippine General Hospital on patients with allergic rhinitis and/or bronchial asthma. Blood samples were collected from patients who developed wheal diameters of 3 mm or more than the negative control. Sera were tested against the same pollen extracts using ELISA.

RESULTS

Of the one hundred sixty-five (165) patients who submitted for skin prick test, 129 showed positive SPT results to the pollen extracts. Weeds were the most sensitizing (51.9%-58.1%). Blood samples were collected from these patients and tested for sIgE ELISA and among them, 71 were positive in the sIgE ELISA. Highest sensitization rates in sIgE ELISA were found in coconut, pigweed, Johnson grass, and rice. The highest positive agreements or the proportion of patients with positive sIgE ELISA among those with positive SPT were in coconut, followed by Johnson grass, pigweed, and rice. Most of the pollen sensitized patients on SPT are polysensitized.

CONCLUSION

SPT is a safe, simple, and rapid method for the diagnosis of IgE-mediated allergy. The lower number of positive patients in sIgE ELISA may be attributed to the low serum IgE levels and low quantities of effectual allergen components in extracts. Results of both SPT and ELISA must be correlated with a patient's clinical history, particularly the patient’s exposures, and physical examination.

Pollen ; Rhinitis ; Asthma

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.

Plants ; Pollen ; Allergens ; Amaranthus ; Arecaceae