The immunohistological localization of γA, secretory "piece" (SP), and lactoferrin (LF) in the mucosae of a variety of normal human tissues was investigated using specific fluoresceinated antisera. γA staining was localized in the apical portion of the mucosal epithelium, intercellular spaces, basement membrane area, and plasma cells of the interstitium or lamina propria of a number of normal human tissues.
SP was ubiquitous in the mucosal epithelium of all tissues studied which included parotid and submaxillary glands, bronchi, pancreas, GI tract, sweat glands, kidney, and gall bladder. In addition, SP staining was localized in the intercellular spaces and on the surface of the epithelial cells lining the lumen of the secretory glands. No SP staining was observed in the plasma cells of the interstitium or lamina propria surrounding the secretory glands in these tissues, and no SP staining was observed in sections of normal spleen or lymph node tissue. SP staining was observed in the sweat glands, pancreas, and kidney in the absence of γA staining.
LF was much less ubiquitous in the epithelial cells of the various tissues studied and appeared to be restricted primarily to the acinar epithelium of the bronchial mucosae, parotid, and submaxillary salivary glands, and was also found in renal tubular cells.
A hypothetical model for the transport of γA and SP across mucosal membrane epithelium is presented.