IMMUNOHISTOCHEMICAL LOCALIZATION OF THE BETA-SUBUNIT OF PROLYL 4-HYDROXYLASE IN HUMAN ALVEOLAR EPITHELIAL-CELLS

The beta subunit of prolyl 4-hydroxylase, the protein-disulfide isomer ase (PDJ), catalyzes the hydroxylation of proline residues of collagen s and proteins with collagen-like structure, a step essential for the folding of the procollagen chains to form triple-helices. In the prese nt study, we report the selective immunohistological localization of P DI in type II alveolar and bronchial epithelial cells. The detection o f the hidden antigen with the monoclonal antibody 5B5 is usually not s uccesful in paraffin sections but was possible after microwave pretrea tment of tissue sections. In cases of severe lung injury (fibrosing al veolitis) enhanced immunoreactivity was found for this enzyme in epith elial, endothelial as well as interstitial cells and in alveolar macro phages. The results indicate a possible involvement of the pulmonary e pithelial cells in the upregulation of collagen production during the process of fibrosis.