Proline-oxidase and hydroxypyroline-2-epimerase activities in experimental fibrosing granulomatous processes of the lung.

Three experimental fibrosing granulomatous processes of the lung (pulmonary granulomas induced by complete Freund adjuvant, viral pneumonitis induced by the A2 influenza virus, and tuberculosis induced in animals exposed to tobacco smoke) were produced in rabbits and the results confronted in view of establishing some relationships between mesenchymal cell accumulations, reticulin fibrillogenesis, and the enzymic activities of proline-oxidase (PO) and of hydroxyproline-2-epimerase (HEP), enzymes intervening in the control of hydroxyproline incorporation in the procollagen molecule. Histopathologic, histochemical and histoenzymic methods, quantification of cells and fibrils, statistical analyses, including the regression lines method, were used. The confrontation of the three processes made obvious that the cell accumulation invariably preceded the fibrillogenetic process, that the immune nature of the process was accompanied by larger cell accumulations than the non-immune one, that between cell accumulations and fibrillogenesis there existed highly significant correlations, and that the increase of the enzymic activities of proline-oxidase and of hydroxyproline-2-epimerase always accompanied these tissular changes, being topographically coincident with them (interlobular areas, alveolar walls).