Lectins and antibodies against blood-group antigens as tools for studying the cellular source of glycoproteins in human bronchial fluid: A comparison of morphological and biochemical observations

We used nine lectins and three antibodies directed against ABO blood-group antigens in morphological cal and Western-blot experiments to investigate the source of secretory products of human large airways. In tissue sections, the lectins from Griffonia simplicifolia (type I B4), Dolichos biflorus, and Helix pomatia, and the antibodies to the A, B, and/or H-antigen bound to mucous gland cells and to goblet cells; the binding of these substances was dependent on secretor status and ABO blood group. The lectins from Arachis hypogaea, Lens tetragonolobus, Ulex europaeus (type I), Triticum vulgaris, and Sambucus nigra bound to these cell types, regardless of ABO blood group. Serous cells of the tracheal and bronchial glands were stained by the lectins from Canavalia ensiformis, T. vulgaris, Lens tetragonolobus, S. nigra, and U. europaeus (type I). On Western blots of bronchial proteins, the mucins in the high molecular weight region exhibited the same lectin and antibody binding as the mucous gland cells and the goblet cells in the histochemical preparations. The low molecular weight bands were characterized by similar lectin- and antibody-binding properties as the serous gland cells. Thus, mature mucins in the large airways are produced only in the mucous cells of the glands and in the goblet cells, whereas fully glycosylated low molecular weight glycoproteins originate only from the serous cells of the glands.