IMMUNOCYTOCHEMICAL DETECTION OF GROWTH-FACTORS (PDGF AND TGF-BETA) INEQUINE CHRONIC PNEUMONIA

The roles played by platelet-derived growth factor (PDGF) and transfor ming growth factor beta (TGF beta) in the development of pulmonary fib rosis in equine chronic pneumonia varied greatly. Macrophages, epithel ial cells and fibroblasts were identified as a source of PDGF, the pri ncipal role of which was related to its mitotic effect on epithelial c ells, and particularly on fibroblasts in the final phase of the diseas e. TGF beta was detected in epithelial cells in all three phases of th e disease and in fibroblasts in the last phase. However, the role of T GF beta in this pulmonary disease is not clear because its expression in the cytoplasm of fibroblasts in areas of strong collagenation durin g the last phase was weak. Nonetheless, it was responsible for the pro duction and release of collagen during the stage of total fibrosis.