The direct basophil degranulation test and the intracutaneous test: a comparison using food extracts.

The purpose of this study was to compare the direct basophil degranulation test (DBDT) of Hirsch and Zastrow with the intracutaneous (IC) test in subjects with and without histories of food allergy. The DBDT was perfomred by incubating the concentrated leukocytes of subjects with dilutions of the suspected allergenic extract and comparing the number of nondegranulated basophils remaining in the test samples with the number remaining in a control. The test sample with the least number of basophils represents maximal basophil degranulation. The DBDT was perfromed with extracts of the suspected food on 14 subjects with reliable clinical histories and positive IC tests indicative of food hypersensitivity. Thirteen of these 14 food-sensitive subjects also had IC and DDBT8 to the extracts of foods to which they were not clinically sensitive. Fourteen different subjects not allergic to foods were also tested with food extracts by the IC and DBDTS. There was a 92% correlation between the IC test and the DBDT, a 90% correlation between the IC test and the history, and an 86% correlation between the DBDT and the history. We conclude that, in this study of subjects clearly sensitive to foods, the DBDT correlates favorably with the history and IC test.