We identified and purified six human noncollagenous protein molecules that specifically bind to serum IgA from patients with coeliac disease, and which as a combination can act as true antigen to reticulin antibodies. In affinity chromatography, the purified human protein molecules removed antibodies against reticulin and endomysium from serum samples of coeliac disease patients. We postulate that an autoimmune mechanism operates in generating the jejunal damage in gluten-sensitive enteropathy and that the human protein molecules described here act as self-antigens in the disease.