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Blood samples from 49 subjects were submitted to cytotoxic leukocyte tests, which were read double-blind by two laboratory technicians. The results were identical in 78% of the tests and the statistical error of the method was 0.46. In a group of 32 subjects, the cytotoxic test was repeated on 3 consecutive days. Deviations in the results occurred in 18--20% of the tests, the statistical errors varying between 0.38 and 0.43. In a series of serum samples (75 subjects) with positive leukocyte reactions to food antigens, various in vitro procedures were carried out in connection with the cytotoxic test. The following observations were made: In 42 of 58 tests, a positive leukocyte reaction was transferred with the reactive serum to cells from non-reactive subjects. After heating of the reactive serum (56 degrees C, 2 h) and washing of the cells, reactivity was no longer observable in 44 out of 52 tests. Treatment with EDTA consistently blocked expected cytotoxic reactions in 36 tests. DSCG inhibited expected reactions in 45%, antihistamine in 93%, and cortisone in 20% of the tests.

A short summary of the literature about the cytotoxic leucocyte test was presented. The results of 1824 CLTs involving 23 food allergens were analyzed. Of the foods tested malt, orange, rye, milk, corn, tomato, oats, wheat, brewers yeast and rice were the ten foods giving a reaction most often in the CLT. Except for minor differences the foods were the same as earlier reported to cause reactions most frequently. Age was found to influence the results of the CLT as cow milk caused reactions most frequently with children and while malt with adults. In 92.1% of the tests there was at least one reaction which means that the CLT is quite sensitive. Thus the CLT seems to be mainly useful for the screening of foods suspected to cause symptoms before planning elimination and provocation trials for the diagnosis of food allergy.