Background Skin tests and tests for IgE antibodies show that subjects are usually sensitive to a number of different pollens, frequently from taxonomically diverse species which are assumed to be allergenically non-crossreactive. This suggests that the presence of IgE antibody-reactivity to an individual pollen may not necessarily have resulted from contact with that pollen or even with a taxonomically closely related species.
Objective Since this has important consequences for allergen avoidance and desensitization of patients, we attempted to define allergenic relationships between diverse pollen species.
Methods Sera from subjects were examined in direct IgE antibody binding experiments and by quantitative inhibition, protein blotting and adsorption and edition studies.
Results Sera from subjects diagnosed as allergic to white cypress pine. Italian cypress. ryegrass or birch pollen were shown to have IgE antibodies that reacted with pollens from these four species and from cocksfoot, couch grass, lamb's quarter, wall pellitory. olive, plantain and ragweed. These reactions were confirmed in protein blotting and adsorption and elution studies where numerous IgE-binding bands were detected in all 11 different pollen extracts with sera from each of the different allergic categories, further evidence of allergenic (i.e. IgE-binding crossreactivity between the different pollens was provided by inhibition studies in which clear-cut inhibitions of IgE binding to the different pollen allergen discs were obtained with comparable amounts of the different pollen extracts.
Conclusion We conclude that the presence of pollen reactive IgE antibodies may not necessarily be a true reflection of sensitizing pollen species.