Interrelationships between skin and humoral tests for immediate hypersensitivity to wheat and indicators of respiratory disease were examined in 176 male bakers. Skin tests were assessed by measuring the diameter of the weal resulting from prick innoculation of allergen extract and circulating allergen-specific IgE by radioallergosorbent test (RAST). Fifteen per cent of subjects showed positive skin-prick test responses to wheat extracts. These subjects demonstrated an increased prevalence of respiratory symptoms and of measurable bronchial responsiveness to methacholine. Thirty per cent of subjects had positive skin test responses to common allergens but negative responses to whole wheat. Compared to subjects with no positive skin test responses they had an increased prevalence of bronchial responsiveness to methacholine but a similar prevalence of respiratory symptoms.
There was a significant association between skin test responses to whole wheat and skin test responses to common allergens suggesting that bakers with pre-existing sensitivity to common allergens are at increased risk of developing wheat flour sensitization.
There was no significant difference between skin-prick test and RAST responses to wheat, water-soluble wheat protein and common allergens. Both tests showed similar relationships with indices of respiratory disease. The associations between skin test and RAST responses to wheat extracts and indices of respiratory disease was stronger for the water-soluble wheat proteins than for other wheat grain extracts.
These results suggest that immediate hypersensitivity to wheat flour is important in the development of non-specific bronchial hyperreactivity in bakers and that the water-soluble fractions of wheat flour are the most important allergenic components. It agrees with in vitro results showing that water-soluble wheat proteins bind IgE in sensitive bakers more closely than other grain extracts.