[Detection of IgE antibody to Pityrosporum orbiculare in patients with atopic dermatitis].

A lipophilic yeast, Pityrosporum orbiculare, found in normal microflora of the human skin, is considered to be a pathogenic allergen of atopic dermatitis (AD). We measured IgE antibody to P. orbiculare using a CAP RAST FEIA kit in 44 patients with AD (AD alone 17, AD+bronchial asthma (BA) 27). The incidence of positive RAST was 88.2% in the patients with AD alone and 74.1% in the patients with AD+BA. The IgE RAST index was 2.77 +/- 1.34 (mean +/- SD) in severe AD patients (n = 23), which was significantly higher than that in mild AD patients (1.88 +/- 1.41, n = 21). The patients with eczematous skin on the face, neck and scalp (n = 27) showed higher IgE titers (2.79 +/- 1.26) than those without skin lesions (1.64 +/- 1.44, n = 17). These results suggest that P. orbiculare is a pathogenic allergen of severe AD. IgE levels for P. orbiculare showed a statistically significant relation to those for Candida albicans (r = 0.62, p < 0.01). In RAST inhibition tests on five patients' sera, C. albicans extract significantly inhibited IgE RAST to P. orbiculare in only one serum, indicating that P. orbiculare shares some IgE binding epitopes with C. albicans, but that P. orbiculare-specific epitopes also exist.