Heterogeneous distribution of mast cells in lichenified lesions of atopic dermatitis

The aim of the present study was to determine whether the number of mast cells in lichenified lesions of atopic dermatitis (AD) have a relationship to familial background of atopic respiratory disease (ARD). We obtained biopsy specimens of lichenified lesions from 59 consecutive patients with AD. They included 35 AD patients who had a personal history of ARD, 9 AD patients without a personal history of ARD but with a family history of ARD, and 15 "pure" AD patients without a personal or a family history of ARD. From each biopsy specimen, 4 microns-thick paraffin-embedded sections and/or 1 micron-thick Epon-embedded sections were prepared, and stained with Giemsa's reagent. With both methods of preparation, the sections from AD patients with a personal history of ARD showed significantly greater mast cell number in lichenified lesions than the "pure" AD patients. It is suggested that the increase of mast cells often seen in AD lesions may be characteristic of a subgroup of AD patients who have a predisposition for ARD.

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.