Abstract
Graft rejection is a crucial complication after heart transplantation. The Billingham rejection grade scoring system is commonly used around the world for estimating graft rejection. To develop a more precise method to decide the rejection grade we attempted to decide the rejection grade by measuring the residual myocardial area after heart transplantation. The hearts of F344 rats were heterotopically transplanted into the abdominal cavity of Lewis rats. Cyclosporin A was administered intramuscularly for 20 days after heart transplantation. The grafted hearts were harvested 30, 40, 50 and 60 days after transplantation and the rejection grade was evaluated by Lurie's method. The same specimen was stained with the azan-Mallory method and the percentage of residual normal myocytes was calculated using a computerized image analyser. The rejection grades worsened with time after transplantation. In contrast, the percentage of residual normal myocardial area decreased with time after transplantation. There was a significantly negative correlation between the rejection grade and the percentage of residual normal myocytes (r=0.76). In conclusion, the assessment of graft rejection by measuring residual myocardial area is useful.
