The property of myofibroblasts in cases of diffuse alveolar damage (DAD) and accelerated pulmonary fibrosis (APF) *
Autopsy tissues obtained from 20 cases of adult respiratory distress syndrome (ARDS) were clinically classified in two groups ; diffuse alveolar damage (DAD) with obvious etiology (9 cases) and accelerated pulmonary fibrosis (APF) with unknown etiology (11 cases) and studied immunohistologically for the participation of myofibroblasts in the development of fibrosis. In the exudative stage (acute stage) of DAD with hyaline membrane, the pulmonary interstitial cells were fibroblasts with only vimentin positivity, but in the proliferative stage (organizing stage), they became myofibroblasts with vimentin and a-smooth muscle actin immunopositivity but without desmin. Likewise, in the cases of APF, the pulmonary interstitial cells were myofibroblasts with vimentin and a-smooth muscle actin immunopositivity but without desmin in most cases. In one case, however, in which intraluminal diffuse fibrosis was dominant, the pulmonary interstitial cells were myofibroblasts with vimentin, and both a-smooth muscle actin and desmin immunopositivity. These results suggest that myofibroblasts play an important role in the formation of the intraluminal fibrosis of both DAD and APF, and the properties of myofibroblasts differ with the stage of intraluminal fibrosis. (Accepted on April 12, 1997) Kawasaki Igakkaiski 23(1) : 27―34, 1997
