Mucosal secretory IgA and secretory piece in adult coeliac disease

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. 11 S IgA and secretory piece were localized to the upper third of the epithelial cells of both surface and glandular epithelium in aUl groups of patients. However, in the untreated coeliac patients fluorescence was also demon-strated 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 1 1S IgA is proposed as well as an additional pathway involving a 'backflow ' of 11S IgA into the lamina propria in patho-logical 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 anti-gens such as gluten. The major antibody found in human secretions is secretory IgA (11S) which differs from serum IgA (7S) in having a higher molecular weight and thus a higher sedimentation coefficient (11S rather than 7S) (Tomasi, Tan, Solomon, and Prendergast, 1965). This increase is due to a component known as secre-tory piece, a glycoprotein found in the gastrointes-tinal epithelial cells (South, Cooper, Wollheim