Studies on the structural basis of immunoglobulin secretion

Selected areas of the gastro-intestinal tract of several mammalian species were studied using histochemical, immunohistochemical and ultrastructural techniques. Immunoglobulin A was found in plasma cells of the lamina propria and in columnar epithelial cells of intestinal glands. The position and distribution of intra-epithelial IgA corresponded to that of glycoprotein-containing cytoplasmic granules, and the hypothesis was advanced that the granules represent secretory inclusions and sites at which IgA of plasma cell origin was aggregated prior or subsequent to combination with secretory piece of epithelial origin. The results of investigation of this propoisition by analysis of subcellular fractions of homogenates of intestinal mucous membrane were inconclusive, possibly due to the heterogeneity of cell types present. [...]