EVALUATION OF THE GUT MUCOSAL BARRIER - EVIDENCE FOR INCREASED ANTIGEN TRANSFER IN CHILDREN WITH ATOPIC ECZEMA

Background: Intestinal antigen handling determines subsequent immune r esponse to the antigen. Antigens are absorbed across epithelium along two functional pathways. The main pathway is degradative, which reduce s the immunogenicity of the antigen. A minor pathway allows the transp ort of intact proteins, which is crucial for antigen-specific immune r esponses. The ussing chamber method allows the quantitative measuremen t of protein transfer across the intestinal mucosa. Objective: This st udy was designed to explore the theory that altered antigen transfer a cross the intestinal mucosa is a factor in the pathogenesis of atopic eczema, characterized by hyperreactivity to environmental antigens. Me thods: The adsorption and degradation of horseradish peroxidase (molec ular weight, 40,000 d) were studied in vitro in Ussing chambers. Eight een biopsy specimens of upper small intestinal mucosa from 14 patients (aged 0.5 to 8 years) with atopic eczema and 18 specimens from 15 age -matched control subjects were examined. Results: The mean (95% confid ence interval) absorption of intact horseradish peroxidase was signifi cantly higher in children with atopic eczema than in control subjects: 242 (81-404) pmol . hr(-1). cm(-2) versus 23 (12-33) pmol . hr(-1). c m(-2); t = 2.86, p = 0.007. The absorption of degraded horseradish per oxidase was 972 (732-1213) pmol . hr(-1). cm(-2) in patients with atop ic eczema and 672 (532-811) pmol . hr(-1). cm(-2) in control subjects; t = 2.29, p = 0.03. Conclusions: Our results may reflect a primarily altered antigen transfer in patients who have atopic eczema, which may initiate and perpetuate prompt immune responses to common environment al antigens, including foods.