CROSS-REACTIVITY BETWEEN CUPRESSUS-ARIZONICA AND CUPRESSUS-SEMPERVIRENS POLLEN EXTRACTS

Background: Cupressus arizonica and C. sempervirens, two species belon ging to the Cupressaceae family, are recognized as an important cause of respiratory allergies in countries with a Mediterranean climate. Ob jective: The relationship between pollen extracts from these two speci es was studied by evaluating the reactivity with polyclonal rabbit ant isera and human IgE. Methods: The two extracts were analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Cross-reactivity w as evaluated by ELISA and immunoblotting inhibition experiments. Resul ts: The electrophoretic patterns of the two extracts are quite differe nt, although some components display identical molecular weights. The immunoblotting developed with human IgE from subjects allergic to memb ers of the Cupressaceae family indicated that two major IgE-reactive c omponents, displaying molecular weights of about 43,000 and 36,000 d, were similarly detected in both extracts. Inhibition experiments showe d a high degree of cross-reactivity between the two extracts when test ed with rabbit polyclonal antibodies against C. arizonica and C. sempe rvirens. When tested with human IgE inhibition methods, both extracts were able to reciprocally inhibit all of the IgE-reactive bands, altho ugh C. arizonica extract was always a better inhibitor. Conclusions: C . arizonica and C. sempervirens extracts are highly cross-reactive at the IgE level and share a number of common epitopes also identified by polyclonal rabbit antisera.