Discovering allergens

Antigenicity of the pollen proteins of various cultivars of Olea europaea

The incidence of positive skin test responses among atopic subjects with suspected respiratory allergy was investigated with commercial and autochthonous pollen extracts of various cultivars of Olea europaea. Pollen was collected from olive trees of well-defined cultivars, extracted, and separated by SDS-PAGE. Immunoblots were used to identify the various IgE-binding proteins of the pollen extracts of the various cultivars. The results revealed six predominant IgE-binding bands, some of which appear in all the cultivars examined. The 18-20-kDa band (Ole e 1) appeared in only eight of the cultivars, but not in the nine others. The presence of specific IgE-binding bands in the various pollen extracts and their correlation with the incidence of positive skin tests are discussed.

Anacardium occidentale (cashew) pollen allergy in patients with allergic bronchial asthma

BACKGROUND

The cashew tree grows in abundance in the hills and plains of Goa, India. Because of the financial yield, more and more trees are being planted each year. The cashew tree flowers once a year between January and March, but pollination is mostly entomophilous.

OBJECTIVE

For the first time, a study was conducted to establish the possible role of the cashew pollen in triggering allergic asthma.

METHODS

A stock solution of pollen extract was prepared with the standard weight/volume method for intradermal skin tests and a bronchial provocation tests (BPTs). The protein content of the antigen, estimated with the use of Folin phenol reagent and a spectrophotometer, was 28.72 mg/ml. Ten healthy volunteers and 65 subjects with allergic asthma, as documented by previous positive skin test reactions to various pollens, were studied.

RESULTS

Of the 65 patients, 26 (40%) had positive skin test reactions in various grades. BPTs were performed in 22 of the 26 patients after their baseline peak expiratory flow volume was assessed. Twenty (90.9%) patients had a positive BPT result, and the majority of patients had grade III and grade IV reactions. None of the control subjects (n = 10) had positive responses to either intradermal tests or the BPT. Serum IgE levels, estimated by ELISA, were high in patients with positive skin test responses and showed a linear correlation with cutaneous sensitivity. Control subjects showed normal levels of IgE (39.0 +/- 7.87 IU/ml).

CONCLUSIONS

This study provided us with knowledge of an additional pollen, Anacardium occidentale, which could trigger an asthmatic response in allergic individuals.