Allergy To Pollen Of Six Common Grasses In The Highlands Of Madagascar

Aim: Few studies have investigated allergy to tropical grass pollen in the highlands of Madagascar where savanna and grassland cover extensive areas. The aim of this work was to study the prevalence of allergy to common grass pollen from these areas. Method: We studied the prevalence of allergy to IgE-binding proteins from six common highland grass pollens and cross-reactivity between the pollen allergens, using the skin-prick test (SPT) and isoelectric focusing (IEF) immunoblot. Sixty-five grass-pollen-allergic patients from the Antananarivo region were selected on the basis of their seasonal atopic symptoms. Results: When comparing SPT and immunoblot results, it was clear that, with the exception of one species, Cynodon dactylon, cross-reactivity of patient serum IgEs with pollen proteins was more visible in SPT responses than in immunoblots. Pollen allergens from either tropical or temperate grass, like Dactylis glomerata, inhibited the IgE reactivity of sera from Rhynchelytrum repens pollen-sensitive patients. Conclusion: This is the first report of cross-reactivity between these six pollen allergen sources. Among them, R. repens pollen was the dominant source of allergens. The allergens of the tropical grass pollens studied have a high impact on Madagascan grass-pollen-allergic patients and could also have a real impact on patients from other regions worldwide where some of these grasses are present, mainly as invasive weeds.