IgE-binding components in Pityrosporum orbiculare identified by an immunoblotting technique.

IgE-binding components in crude extracts of Pityrosporum orbiculare were separated by sodium dodecylsulphate polyacrylamide gel electrophoresis and transferred to Immobilon membrane. The components were detected by P. orbiculare radioallergosorbent (RAST) positive sera (class 2-4) from 37 patients with atopic dermatitis and visualized by enzyme-labelled anti-human IgE antibodies in chromogenic substrate. Numerous IgE-binding compounds were demonstrated in the molecular weight (MW) range of 14-94 kD. Eight of them were characterized to molecular size, frequency of reacting sera and intensity of bands. Six of the defined components were found to be major allergens reacting with more than 50% of the sera. They had MWs 86, 76, 67, 28, 17 and 13 kD. Thirty-six of the 37 patients had elevated total serum IgE. Two other patient categories were studied; 11 patients with lymphatic filariasis (high total serum IgE, greater than 1,300 kU/l) and 15 pityriasis versicolor patients (normal total serum IgE, less than 122 kU/l). The P. orbiculare RAST values for these sera showed good accordance with the reactivity in immunoblotting experiments.