Ultrastructural localization of the low molecular weight protease inhibitor in human bronchial glands.

Light microscopically the low molecular weight protease inhibitor (LMI) and lysozyme have both been demonstrated in the cytoplasm of serous cells of bronchial glands. By immunoelectron microscopy LMI was demonstrated in secretory granules of these serous cells. Many granules showed a peripheral or bean-shaped staining pattern, other granules were uniformly stained or not stained at all. In contrast to this latter finding, virtually all granules were found positive for the presence of lysozyme, suggesting that there is no association of LMI with lysozyme at the ultrastructural level.