Immunohistochemical quantitation of three collagen isotypes in perfused areas and nonperfused foci of the lungs of irradiated mice

Collagen isotypes I, III, and IV were quantitated by video image analysis of fluorescent-antibody-stained lung tissue sections from control and irradiated C57L/J and BALB/c mice. The perfusion status of lungs was determined by injecting colloidal carbon into the hepatic vein immediately prior to sacrificing the animals. Well-perfused parenchymal regions turned black, whereas nonperfused areas remained pale. Previous histological studies indicated substantial differences in the types of lesions found in the lungs of these two strains. C57L/J mice develop extensive and persistent contracted fibrosis. In lung sections of C57L/J mice examined 28 weeks after a dose of 11 Gy X rays, all three collagen isotypes were significantly elevated to levels 37-51% higher than age-matched control values in perfused regions of lung. In nonperfused areas, which had the histological appearance of contracted scar tissue, the three collagen isotype levels were further elevated to values 83-90% greater than controls. This finding suggests that in C57L/J mice, an elevation of each or all of the three collagen isotypes to levels approximately 45% greater than controls is consistent with continued pulmonary function during the intermediate phase of lung damage, whereas areas of parenchyma containing isotype levels in excess of 185% of control values coincide with functionally deficient regions. BALB/cCr at sign Alt. mice examined 28 weeks subsequent to 14.5 Gy X rays had a variety of visible lesion, most of which were nonperfused. In addition, one-quarter of nonperfused acini had no visible lesion. In perfused areas, the three isotypes were increased to 119-132% of control levels, with a further, significant (P less than 0.05) increase to 128-144% of control values in nonperfused parenchyma