High dose grass pollen tablets used for hyposensitization in hay fever patients. A one-year double blind placebo-controlled study.

Previous, placebo-controlled clinical trials with oral hyposensitization in grass pollinosis have been disappointing. Since the results possibly could be explained by too low doses of ingested allergens, the present study was initiated to evaluate the effect of high doses of allergens. Forty-two adults with symptoms in the grass pollen season and with grass pollen sensitivity demonstrated by skin prick test and conjunctival provocation test were included. Enterosoluble tablets were administered daily for 1 year. Twenty-two patients, who completed the study, received placebo and 17 mixed grass pollen allergens from rye grass, timothy grass, cultivated rye and velvet grass. Evaluated either by self-assessment or by symptom and medicine score before and after treatment, the group receiving pollens did not improve clinically compared the controls. During the study, conjunctival sensitivity decreased equally in the two groups, and changes in specific IgE, allergen-induced histamine release from blood cells and skin prick test were insignificant and with no difference between groups. Five patients, who received pollen allergens, had episodes of urticaria or angioedema, and a further three patients on the same treatment had slight gastrointestinal side effects. In conclusion, enterosoluble grass pollen allergens in contrast to birch pollens did not have any therapeutic effect, even in doses more than 4,000 times higher than those used for subcutaneous hypersensitization. The reason may be degradation of allergens before the immune system is reached.