Clinical application of histamine prick test for food challenge in atopic dermatitis

Determining positive food challenges are not easy as there is an absence of simple and objective tests. Histamine, an essential mediator for allergic reactions, is involved in the pathogenesis of atopic dermatitis (AD) and food challenges can change histamine levels. The significances of a prick test with histamine (histamine prick test, HPT) relating to the interpretation of food challenges in AD were evaluated. A total of 467 AD patients participated in this study. Skin prick tests, identification of specific IgE and open food challenge were conducted for the identification of food allergy. Elimination diet was performed with HPT. HPTs were conducted before and after food challenges. The wheal sizes by HPT were significantly decreased after an elimination diet. The relative changes of wheal sizes significantly correlated with those of clinical severity scores in AD patients (p<0.001). The wheal sizes in HPT were increased with a positive provocation in open food challenges. In conclusion, HPT may be a simple and objective test to interprete the results of food challenges in patients with AD. The exact mechanisms of the changes in skin reactivity by HPT need further investigation.