Hypersensitivity to pollen of four different species of Brassica: a clinico-immunologic evaluation in patients of respiratory allergy in India

BACKGROUND: Rapeseed-mustard is the second most important source of edible oil in India. Several species of Brassica are grown in different parts of country for its oilseeds. OBJECTIVE: The objective was to investigate allergenicity to antigenic extracts of pollen of 4 species of Brassica. METHODS: Brassica campestris, Brassica juncea, Brassica nigra, and Brassica napus were selected for the detailed investigation. Pollen samples from each of the four species were collected from the polliniferous materials. The antigenic and allergenic profiles of these extracts were evaluated by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Skin prick test, enzyme linked immuno sorbent assay and Western blot on atopic individuals. RESULTS: Out of the 159 atopic subjects tested, 21.38% were positive to at least one or other species of Brassica pollen, with highest skin positivity (13.20%) to B. campestris extract. Raised IgE with significant linear correlation with intensity of skin reactions was obtained. Protein fractions of 20, 25, 32, 37, 56, and 90 kDa were recognized by B. campestris and B. juncea whereas 56, 76, 87, and 90 kDa were recognized by B. nigra and B. napus as major IgE binding protein fractions. The patients also showed positivity to other inhalant pollen allergens tested. CONCLUSION: IgE mediated hypersensitivity varied from 4.40% to 13.20% in Indian atopic subjects to pollen of one or the other species of Brassica. Protein fractions of 47, 56, 76, 87, and 90 kDa were identified as IgE binding by all the four species, however individual heterogeneity exists. Thus a local species may be more pertinent for immunotherapy. The major allergen needs to be further characterized.