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The vitronectin receptor (integrin αvβ3), a cell-surface adhesion receptor, has been shown to play a significant role in endothelial cell migration, apoptosis, atherosclerosis, and T-lymphocyte activation. This study was undertaken to test the hypothesis that cardiac allograft rejection is associated with increased expression of αvβ3. We also determined whether fibronectin receptor (α5β1) and tissue factor are up-regulated in the presence of acute cellular rejection. We evaluated endomyocardial biopsy specimens with histologic evidence of different degrees of acute cellular rejection (grade 0, n = 10; grade 1A, n = 10; grade 2, n = 10; grade 3A, n = 10). Biopsies were obtained 2–4 weeks after cardiac transplantation. Immunoperoxidase staining was performed for αvβ3, tissue factor, and α5β1, and protein levels were further determined by Western blot analysis. Specimens with grade 2 and grade 3A rejection showed positive staining of αvβ3 in lymphocytic aggregates and vascular endothelial cells. By immunoblotting, we identified significantly increased expression of αvβ3 in the presence of acute rejection, grade 2 (3-fold, p = 0.01) and grade 3A (3.6-fold, p = 0.005) compared to grade 0 and 1A specimens. There was no evidence of increased expression of α5β1 or tissue factor. Acute cellular rejection, a process characterized by T-lymphocyte activation and release of inflammatory cytokines, is associated with increased expression of αvβ3. The vitronectin receptor (integrin αvβ3), a cell-surface adhesion receptor, has been shown to play a significant role in endothelial cell migration, apoptosis, atherosclerosis, and T-lymphocyte activation. This study was undertaken to test the hypothesis that cardiac allograft rejection is associated with increased expression of αvβ3. We also determined whether fibronectin receptor (α5β1) and tissue factor are up-regulated in the presence of acute cellular rejection. We evaluated endomyocardial biopsy specimens with histologic evidence of different degrees of acute cellular rejection (grade 0, n = 10; grade 1A, n = 10; grade 2, n = 10; grade 3A, n = 10). Biopsies were obtained 2–4 weeks after cardiac transplantation. Immunoperoxidase staining was performed for αvβ3, tissue factor, and α5β1, and protein levels were further determined by Western blot analysis. Specimens with grade 2 and grade 3A rejection showed positive staining of αvβ3 in lymphocytic aggregates and vascular endothelial cells. By immunoblotting, we identified significantly increased expression of αvβ3 in the presence of acute rejection, grade 2 (3-fold, p = 0.01) and grade 3A (3.6-fold, p = 0.005) compared to grade 0 and 1A specimens. There was no evidence of increased expression of α5β1 or tissue factor. Acute cellular rejection, a process characterized by T-lymphocyte activation and release of inflammatory cytokines, is associated with increased expression of αvβ3.
Yamani et al. (Fri,) studied this question.