A CASE RETAINING CONTACT URTICARIA AGAINST EGG-WHITE AFTER GAINING TOLERANCE TO INGESTION

A girl, 5.7 years old, gained tolerance to egg white ingestion in spit e of high immunoglobulin E (IgE) antibody titers to egg white but reta ined contact urticaria against egg white. She developed atopic dermati tis on her face at 2 months of age and showed high IgE antibody titers to egg white and cow's milk. Accidental ingestion of egg products ini tiated immediate symptoms such as wheezing, urticaria, erythema and ed ema of the eyelids and conjunctiva three times. These symptoms were co nfirmed by challenge tests using boiled egg white at 3.9 years of age. She also reacted positively to a 20 min patch test on her volar arm w ith raw egg white. However, there were no reactions to the oral challe nge test by boiled egg and freeze-dried egg white at 5.1 and 5.7 years of age, respectively. This non-responsiveness was confirmed by a doub le-blind, placebo-controlled food challenge using freeze-dried egg whi te. Nevertheless, she showed positive reactions to a 20 min patch test with freeze-dried egg white. Her IgE antibody titers to the egg white components including ovomucoid, ovalbumin, ovotransferrin and lysozym e as well as egg white were high from 2.9 to 5.7 years old. Her IgE an tibody titers for the ovomucoid fragments digested by pepsin, chymotry psin and trypsin were not lower than those of positive control subject s. The binding activity of IgE antibody to ovomucoid, however, decreas ed from 2.9 to 5.6 years as shown by radioallergosorbent test (RAST) i nhibition assays. The IgE antibody showed weaker binding activity to p epsin- and chymotrypsin-digested ovomucoid that were filtered through cut-off 10 000 filter at the age of 2.1 and 5.7 years. We speculated t hat the maturation of secretion of digestive enzymes was involved in t he mechanisms of the acquisition of tolerance to egg white ingestion i n spite of the persistence of contact urticaria.