Lymphocyte transformation test for house dust mite in atopic dermatitis: relationship between mite antigens for type I and type IV allergy.

Using a crude extract obtained from Dermatophagoides farinae, and its four fractions (I, II, III and IV) partially purified by high-speed gel filtration chromatography, scratch tests and lymphocyte transformation tests (LTTs) were performed on 37 patients with atopic dermatitis. Crude mite antigen provoked positive scratch test reactions in 25 (68%), and positive LTT reactions in 19 (51%) of the 37 patients examined. Mite antigen fractions I, II, III and IV induced a positive LTT reaction in 19, 22, 17 and 7 patients, respectively. Of the 65 positive LTT reactions, 25 accompanied a positive scratch test to the antigen fraction which provoked the positive LTT reaction, but 40 accompanied a negative scratch test. These findings suggest that house dust mite antigen fractions for type IV allergy are different from those for type I allergy in a considerable proportion of patients with atopic dermatitis.