Characterization of IgE-reactive autoantigens in atopic dermatitis - 2. A pilot study on IgE versus IgG subclass response and seasonal variation of IgE autoreactivity

Previously we reported that patients with severe forms of atopy (e.g, atopi c dermatitis, AD) frequently display IgE reactivity against autoantigens. H ere we investigated the effects of periodate treatment and reducing versus nonreducing conditions on IgE recognition of nitrocellulose-blotted human c ell extracts. IgE and IgG subclass reactivities of AD patients to blotted h uman cellular extracts as well as to ELISA plate-bound purified endogenous (myosin, histones) antigens and an environmental allergen (timothy grass po llen allergen, Phl p 5) were compared. Serum samples were collected over a period of 12 months from 3 autoreactive AD patients with pollen allergy and tested for IgE reactivity to nitrocellulose-blotted human epithelial and e ndothelial cell extracts as well as to birch and timothy grass pollen aller gens. Results obtained indicate that (1) IgE autoantibodies may be directed primarily against protein and not carbohydrate epitopes, (2) reducing cond itions seem to expose or better extract epitopes recognized by IgE autoanti bodies, (3) IgE and lgG1-4 autoantibody responses were poorly associated an d (4) IgE responses to autoallergens may reflect skin manifestations and ma y be boosted by seasonal exposure to pollen allergens. Our results thus ind icate that IgE autoreactivity may represent a true form of autoimmunity dir ected against partly denatured peptide epitopes which may be boosted by exo genous allergen contact.