Ultrastructural localization of bronchial inhibitor in human airways using protein A-gold technique

Gold immunolabelling of human airways using a polyclonal antibody specific for the bronchial inhibitor (brI) demonstrates that this protease inhibitor is present in the serous cells of the bronchial glands. Most of the largest secretory granules (89%) are uniformly stained for brI whereas the smallest granules (diameter less than 80 nm) appear frequently (68%) devoid of brI.