New diagnostic method for pulmonary allograft rejection by measurement of bronchial mucosal blood flow.

We investigated the relationship between the rejection of lung allografts and the bronchial mucosal blood flow with a laser flowmeter. Nineteen mongrel dogs underwent left lung allotransplantation and were given daily oral immunosuppressive therapy with azathioprine and cyclosporine. The bronchial mucosal blood flow at the carina and the bifurcation of left upper and lower bronchi were measured on days 14, 21, and 28 after left lung transplantation. The bronchial mucosal blood flow of the transplanted lungs was expressed as the ratio of bronchial mucosal blood flow at the bifurcation of left upper and lower bronchi to the bronchial mucosal blood flow at the carina (L/C ratio) instead of the absolute value because bronchial mucosal blood flow was affected by the depth of anesthesia of the dogs. We classified the histologic appearance of the transplanted lung tissue into one of five grades: 0, 1a, 1b, 2, and 3. No rejection was in grade 0, and as the rejection process progressed the higher grades were used in order. The mean L/C ratios for grades 0, 1a, 1b, 2, and 3 were 0.95 +/- 0.03, 0.82 +/- 0.05, 0.68 +/- 0.04, 0.58 +/- 0.07, and 0.30 +/- 0.07, respectively. Thus the L/C ratio decreased as the rejection process progressed. The histologic changes of the donor main bronchus in each rejection grade were investigated. Mononuclear cell infiltration and edema around the small vessels was seen in early rejection. These same histologic changes appeared in muscular arteries as rejection progressed, and the damage to the small vessels and muscular arteries was more severe in late rejection.(ABSTRACT TRUNCATED AT 250 WORDS)