Background: Food allergy in early childhood usually resolves with time; however, little is known about predictors for persistence or transience of food allergy in children with atopic dermatitis. The aim of the study was to evaluate whether specific IgE levels in serum could be a useful predictor of the outcome of oral re-challenges.

Methods: In 74 children, 99 oral food challenges were performed (cow milk n = 48, hen egg n = 37, and wheat n= 14) and repeated after a median time interval of 16 months. In 15 of the 74 children, a third challenge (n = 22) could be performed, with a median time interval from second challenge to third challenge of 15 months.

Results: There were 37 children with transient food allergy (positive first challenge and negative second challenge), while 62 children had persistent food allergy (positive first and positive second challenge). Comparison of the two groups showed that specific IgE as well as total IgE in serum was significantly higher in the latter group. However, looking at the time course, specific IgE did not decrease significantly during elimination diet.

Conclusion: Our results indicate that specific IgE in serum - although very helpful at the time of the first diagnosis - cannot predict whether a child will become tolerant after a period of avoidance. Therefore, oral re-challenges remain mandatory.

Key words: allergy, atopy patch test, children, cow milk, DBPCFC, food challenge, hen egg, re-challenge, sensitization, specific IgE