Mucosal secretory IgA and secretory piece in adult coeliac disease.

Immunofluorescence studies with specific antisera to secretory IgA (11S IgA) and secretory piece were carried out on the jejunal mucosa of nine patients with adult coeliac disease (treated and untreated). The results were compared with those obtained in four normal patients and in four patients with local and systemic IgA (7S) deficiency. 11S IgA and secretory piece were localized to the upper third of the epithelial cells of both surface and glandular epithelium in all groups of patients. However, in the untreated coeliac patients fluorescence was also demonstrated in the basement membrane and connective tissue of the mucosa (returning to normal on treatment). On the basis of our findings, a revised pathway for the normal production of 11S IgA is proposed as well as an additional pathway involving a ;backflow' of 11S IgA into the lamina propria in pathological states such as coeliac disease. This backflow is reversed by an adequate gluten-free diet. It is suggested that 7S IgA and 11S IgA may be involved in immune reactions in the mucosa with antigens such as gluten.