Sensitization to oilseed rape is not due to cross‐reactivity with grass pollen

Background Oilseed rape is an important crop grown in the UK which can cause specific immunological sensitization with clinical symptoms in a relatively small number of the general population. Individuals with immunoglobulin (Ig) E‐mediated allergy to oilseed rape have also been found to be sensitized to other pollen allergens, most frequently being grass pollen. Cross‐reactivity between common grass and oilseed rape would have important implications, especially as their flowering period coincides. Objective We have investigated whether the cosensitization found in individuals sensitized to both oilseed rape and grass pollen is due to cross‐reactivity. Methods Cross‐reactivity between oilseed rape and grass pollen was determined using RAST, RAST inhibition, Western blotting and inhibition studies with Western blotting. Results Competitive RAST inhibition studies between pollen of oilseed rape and grass failed to show any cross‐reactivity between the pollen types. Self‐inhibition with oilseed rape resulted in 90% inhibition, whereas there was less than 10% inhibition with grass pollen. Western blotting revealed allergens of similar molecular weight in both oilseed rape and grass pollen. Despite allergens of similar molecular weights being present in both pollen types, inhibition immunoblot studies confirmed that the allergens in the two allergens were immunologically distinct. Conclusion The allergens of oilseed rape and grass pollen, although similar in molecular weights, are immunologically distinct and there is no evidence of cross‐reactivity between them. Individuals allergic to grass pollen will not necessarily develop a specific nasal or airway response to inhaled oilseed rape pollens.