INCREASED EXPRESSION OF INTERCELLULAR-ADHESION MOLECULE-1, CD11 CD18 CELL-SURFACE ADHESION GLYCOPROTEINS AND ALPHA-4-BETA-1 INTEGRIN IN A RAT MODEL OF CHRONIC INTERSTITIAL LUNG FIBROSIS/

The expression of the intercellular adhesion molecule 1 (ICAM-1), and the integrins CD49, CD11b/c, and CD11a(LFA-1 alpha chain) was analyzed in an experimental model of pulmonary fibrosis. Adult rats were expos ed to 75% oxygen during 10 weeks, and to 2.0 mg/kg of paraquat twice w eekly. Rats were sacrificed at 2 days, and at 2 and 10 weeks after the first injection of paraquat. Lungs were fixed in 4% paraformaldehyde and used for histology and immunohistochemistry. At 2 days the lungs s howed a diffuse inflammation composed of a mixed polymorphonuclear and mononuclear cell infiltrate. Afterwards, the inflammatory process was predominantly mononuclear, and an increasing fibroblast proliferation was observed. Early inflammatory events (48 h) correlated with a mode rate increased expression of ICAM-1, LFA, and CD11b/c in epithelial ce lls as well as a pronounced expression of ICAM-1 and CD11b/c in macrop hages. At 2 and 10 weeks, there was a progressive increased expression of CD11b/c and ICAM-1 by macrophages, as well as of LFA in epithelial cells, and of ICAM-1 and CD49 by epithelial and interstitial cells. L ymphocytes showed a slight increased expression of LFA at 2 weeks, and of CD49 at 2 and 10 weeks. These results suggest that macrophages exp ressing ICAM-1, CD11b/c, and CD49 are involved in the earlier and late phases of the disease whereas fibroblast and epithelial cells express ing ICAM-1 and CD49 might play a role in the cell interactions involve d in the fibrotic phase.