Immunohistochemical study of IgA transepithelial transfer into digestive tract secretions in the mouse.

The serum of mice with IgA-secreting transplantable myelomas contains high IgA concentrations, and polymeric IgA with secretory characteristics are observed in the intestinal and salivary secretions. Immunofluorescence was used to demonstrate the transepithelial transfer of these secretory IgAs. IgA molecules were noted within the cytoplasm of intestinal columnar and salivary-secreting cells; they were not present in goblet cells or the salivary-excretory duct cells. Purified IgAs from the intestinal secretions of myeloma-bearing mice possess extra antigenic determinants attributable to an additional secretory piece. A specific antisecretory piece antiserum did not stain either the intestinal columnar cells or the salivary secreting cells, whereas goblet cells and salivary duct cells were shown to contain this piece. Immunofluorescence also showed that IgA and the secretory piece were simultaneously present in the luminal surface of the intestinal epithelium.