CHANGES IN CYTOKERATIN, VIMENTIN AND DESMOPLAKIN DISTRIBUTION DURING THE REPAIR OF IRRADIATION-INDUCED LUNG INJURY IN ADULT-RATS

The expression of cytokeratins, desmoplakin and vimentin has been stud ied immunohistochemically in the rat lung injured by x-irradiation usi ng 14 well characterized monoclonal antibodies. A time-dependent relat ionship between the cytokeratin expression pattern and the morphologic al alterations observed was apparent. A cytokeratin 8 and 18 expressio n in normally cytokeratin 8/18-negative, type I alveolar epithelial ce lls was detectable even at 3-6 h after irradiation. Between 14 days an d 2 months, a remarkable heterogeneity in the epithelial cell cytokera tin pattern and an increasing immunoreaction for desmoplakin was found . In terminal bronchial epithelial cells, a heterogeneous CK8, 18 and 19 staining and a neoexpression of cytokeratins 4 and 7 was detected. Finally, peribronchiolar and vascular smooth muscle cells were cytoker atin-positive. At 6 months after irradiation, cytokeratin 13 and vimen tin were focally present in bronchial epithelial cells and atypical ty pe I and II pneumocytes as well as scattered epithelioid cell complexe s were noted. During the course of injury, a loss of type III alveolar epithelial cells was found, which was characterized in the rat by a s pecific globular cytokeratin pattern and restricted immunoreactivity w ith cytokeratin-specific antibodies. These results show that the expre ssion pattern of cytokeratins is a sensitive marker in monitoring epit helial alterations during lung injury.