Conocarpus trees have low allergenicity potential in patients suffering from asthma and allergic rhinitis living in southwestern Iran

Purpose

Aeroallergens are airborne particles capable of triggering rhinitis and respiratory complications in sensitive individuals. Tree pollen is a major source of aeroallergens and can potentially induce allergic responses in a variety of ways. Thus, studying the allergenicity of urban green spaces is crucial to public health quality. Conocarpus trees have been vastly imported in recent years in Iran for reforestation projects and now have a wide distribution in southern parts of Iran, especially in Khuzestan province. Yet, these plants have not been studied adequately for their allergenic potential. This work aims to evaluate the IgE-mediated skin reactivity to Conocarpus pollen extract in patients suffering from asthma and allergic rhinitis living in southwest Iran.

Methods

Ninety consecutive patients diagnosed with asthma and allergic rhinitis were selected. Mild cases initially and moderate to severe cases after a period of treatment and follow-up underwent skin prick test (SPT) for Conocarpus pollen extract and several other aeroallergens.

Results

A skin prick test was performed for all 90 patients presenting asthma and allergic rhinitis symptoms and treated and followed in an outpatient setting. 17% had weakly positive test results for Conocarpus pollen extract. The maximum mean wheal diameter was 4 mm. For comparison, about 48% of the patient were sensitized to Russian thistle, with a maximum mean wheal size of 12 mm. Sensitization to grasses, some other trees, and indoor allergens were also measured.

Conclusion

Conocarpus trees have a low potential for inducing allergic responses in the studied population. There is no evidence that they have any role in triggering the thunderstorm asthma episodes.