Lectin histochemistry of trachea and lung of healthy turkeys (Meleagris gallopavo) and turkeys with pneumonia.

Thirteen lectins were used to characterize lectin-binding specificity of glycoconjugates on sections of formalin-fixed lung and trachea from seven normal turkeys, two turkeys with acute pneumonia, and two turkeys with chronic pneumonia. Neuraminidase was used to digest sialic acid residues. One N-acetylgalactosamine-binding lectin and two N-acetylgalactosamine/galactose-binding lectins stained the apical membrane and cytoplasm of multifocal cells that lined air atria and hyperplastic granular cells. Other lectins in these groups stained ciliated cells of the trachea and bronchi and air capillary epithelial cells. Sialic acid residues were on apical surfaces of ciliated and nonciliated tracheal and bronchial lining cells, air capillary epithelial cells, and vascular endothelial cells. Mannose/glucose-binding lectins stained reticular and elastic fibers in the lamina propria of trachea, primary and secondary bronchi, and the tunica adventitia of arteries and veins. By transmission electron microscopy, colloidal gold-Arachis hypogaea (peanut agglutinin) labeled microvilli on the apical surface of mature granular cells. The L-fucose-binding lectin, in addition to several other lectins, stained nonspecifically in both trachea and lung. These studies show that granular cells that line air atria can be identified with lectins of N-acetylglucosamine and N-acetylgalactosamine/galactose groups, and that apical surfaces of epithelial cells and endothelial cells in the trachea and lung express terminal sialic acid residues.