POSSIBLE INDUCTION OF FOOD ALLERGY DURING MITE IMMUNOTHERAPY

Sera of 17 patients receiving immunotherapy for house-dust mite allerg y were tested for IgE antibodies against snail and shrimp. Serum sampl es were taken at the start of immunotherapy and 14-20 months later. Wh ile the average IgE response to mite, Der p 1, and Der p 2 did not alt er significantly, the average response to snail showed a significant i ncrease. This included two conversions from negative to strongly posit ive. These novel IgE antibodies against snail were shown to be cross-r eactive with mite. Three patients had a positive RAST for shrimp. For one of them, a strong increase of IgE against shrimp (and snail) was o bserved. In 2/3 snail/shrimp-positive sera, IgE antibodies against the cross-reactive allergen tropomyosin from mite, snail, and shrimp were demonstrated. A clear IgE response to snail (> 10% binding in a snail RAST) was confirmed by a positive skin prick test (SPT) for 6/10 pati ents. The two patients with antitropomyosin IgE also had a positive SP T for shrimp, and demonstrated the oral allergy syndrome (OAS) after e ating shrimp. The observations in this study indicate that house-dust mite immunotherapy is accompanied by the induction of IgE against food s, including tropomyosin-reactive IgE. Food allergy (OAS) was observed in patients that had IgE antibodies against this cross-reactive aller gen. In conclusion, induction of IgE during mite immunotherapy might o ccasionally cause allergy to foods of invertebrate animal origin.