COMPARISON OF TWO DIFFERENT HRT METHODS IN PATIENTS SUSPECTED TO HAVE FOOD ALLERGY AND ANALYSIS OF ANTI-IgE NON RELEASERS AND ALLERGEN NON RELEASERS

Abstract

Histamine release test (HRT) is one of popular and frequently used in vitro tests for identifying causative allergens in patients with allergic disease. Five allergens (egg white, cows milk, wheat, rice, and soy) in 54 children with food allergy were examined by two methods of HRT (Lucica HRT^®, Shionogi^®) and CAP-RAST^®. Positive rate of CAP-RAST^® exceeded that of both methods of HRT. Although in patients with early phase response in allergic reaction, positive rate of HRT exceeded the results of patients without any symptoms. Furthermore, HRT revealed lower sensitivity and higher specificity than CAP-RAST^® in egg white and cows milk.
In addition, we evaluated histamine release to anti-IgE antibody. Seven anti-IgE non releasers were found in 54 patients. All anti-IgE non releasers aged under two years old (0.57±0.8years) and their serum total IgE levels were relatively lower (116±72IU/ml) compared with those of releasers. Also, three of seven non releasers manifested early phase reaction to egg white and/or cows milk.
On the other hand, three allergen (egg white) non releasers were found in 21 patients who showed early phase reaction to egg white. Their percentage of eosinophil in peripheral blood leukocytes were relatively higher than those of releasers (p<0.01). The mechanism and pathogenesis of anti-IgE and allergen non releasers have not been elucidated yet.
HRT might be useful in predicting clinical symptoms. However, there is a limitation of its usefulness. Therefore, we should be careful in choosing clinical test in detecting causative allergens.