Allergens of Pityrosporum ovale and Candida albicans. II. Physicochemical characterization.
Pityrosporum ovale has recently been recognized as a source of allergens to which many patients with atopic dermatitis (AD) show type I skin reactions and specific IgE antibodies. In this study the IgE-binding components and/or epitopes in P. ovale extract were shown to be partially sensitive to pronase or trypsin treatment, whereas periodate oxidation resulted in a complete loss of IgE-binding capacity, thus suggesting the involvement of carbohydrate structures. In Con A affinity chromatography most of the IgE-binding capacity of crude P. ovale extract bound to the column, and could be eluted with mannoside. Gel filtration on Sephacryl S-400 revealed a marked heterogeneity with respect to molecular mass, with most of the IgE-binding activity associated with high-mol.-mass fractions (from 5 x 10(4) up to 2 x 10(6) Da). A similar heterogeneity was found after chromatofocusing, with IgE-binding in the whole pI-range from 7.0 to 4.0. Essentially identical results were obtained with extracts of Candida albicans, in agreement with the previously shown cross-reactivity of IgE-binding components in the two yeast extracts. In inhibition ELISA, gel filtration and chromatofocusing fractions containing components with widely different mol. mass or pI showed complete reciprocal cross-inhibition, and were all capable of inhibiting the binding of IgE to unfractionated extracts. We therefore conclude that the cross-reacting anti-P. ovale/anti-C. albicans IgE antibodies in the sera of AD patients are mainly directed at a restricted number of carbohydrate epitopes that are expressed on a heterodisperse range of high-mol.-mass components, probably mannans or mannoproteins.
Doekes
G
G
Department of Dermatology, University Hospital, Utrecht, The Netherlands.
Kaal
M J
MJ
van Ieperen-van Dijk
A G
AG
D000180:Acrylic Resins; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000910:Antibodies, Heterophile; D000915:Antibody Affinity; D001666:Binding Sites, Antibody; D002176:Candida albicans / Q000276:immunology*; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D003208:Concanavalin A; D003429:Cross Reactions; D007073:Immunoglobulin E / Q000737:chemistry / Q000276:immunology*; D008290:Malassezia / Q000276:immunology*; D008970:Molecular Weight
D000180:Acrylic Resins; D000485:Allergens; D000910:Antibodies, Heterophile; C037239:Sephacryl Superfine; D003208:Concanavalin A; D007073:Immunoglobulin E