Instability of the structure and allergenic protein content in Arizona cypress pollen.

The allergenic characteristics of pollen and their levels of expression may vary depending on the plant species, the degree of maturation and the influence of environmental factors such as climate and atmospheric pollution. The objective of this survey was the comparison of the structure and allergenic protein content in Arizona cypress (Cupressus arizonica, CA) pollen collected just after microsporangia dehiscence and 2 weeks later in urban areas. The morphology and structure of pollen were examined by scanning electron microscopy. Pollen protein content was quantitatively and qualitatively investigated by Bradford protein assay, SDS-PAGE and densitometric analysis respectively. Fifteen allergic subjects, according to their clinical history of seasonal rhino-conjunctivitis and bronchial asthma have been selected for skin prick testing and ImmunoCap using CA standard allergen and for immunoblotting using extracts of CA mature pollen collected from Tehran. After 2 weeks, numerous cracks and collapses appeared in pollen surfaces. Western blotting performed by using extracts of pollen collected from Tehran, revealed that sera-specific immunoglobulin E of all allergic subjects reacted to a 35 kDa protein. The presence of this new major allergen and the decrease of Cup a 1 provide reliable explications about the low efficiency of standard commercial allergens in the diagnosis of the CA pollen allergy in Tehran. The instability of the pollen structure and protein content affects CA pollen allergenic properties. This study also suggests that to optimize CA standard allergen preparations, the eventual variability of pollen allergenic components have to be considered for each region.