Frequency of immediate, late and delayed type food hypersensitivity in provocation test for egg allergy and its correlation with egg-white IgE RAST score

In egg allergy the method to determine the serum level of a specific IgE is associated with shortcomings such as a frequent lack of correlation between the symptoms and the presence of a specific IgE ; furthermore, in an attempt to find an antigen responsible for food hypersensitivity, the development of symptoms in a provocation test does not necessarily guarantee test values that signify positivity (a low sensitivity). In the present study where the egg provocation test was conducted, the correlation of the time required for the symptoms to develop, with the egg white RAST score in egg allergy were examined.

Subjects: Included 125 children with atopic dermatitis (AD), (mean 2 y 10 m, from 3 m to 15 y in age).

The oral provocation test and Result: Approximately 0.1 ml of the raw egg was given first, followed by several spoonfuls (0.15ml/sp), until the entire quantity. In a one-week observation of the patients who were subjected to the egg-loading test, 75 among 125 suffered immediate (type I, 1h>), late (type L, 24h>), or a delayed-type (typed, 1-7d) skin eruption or exacerbation of eczema, while 50 exhibited negative responses to the test. For type I , the positivity and the RAST score was 50.7%, 1.71+/-0.36(95％CI), 12.0%, 1.11+/- 0.81 for type I alone out of them, 2.7%, 1.5+/-2.08 for type IL, 4.0%, 0.33+/- 0.50% for type DI, and 32.0%, 2.17+/- 0.37 for type ILD which is the higher value (P=0.049). 55.6% of type I alone exhibited negative- RAST score.

In conclusion: The type ILD shows higher value of the RAST score, which likely reflects the pathogenesis of the disease such as allergic inflammation  and the severity in the higher value group.