The effects of cyclosporin A on transplanted rat allografts.

Since 1983, Cyclosporin A (CsA) has been the most successful primary drug in preventing rejection of organ transplants. This study was designed to determine the efficacy and dose response of CsA in preventing rejection of LBNF-1 rat allografts to Lewis recipients. Four groups of animals were studied. Group I served as the control, and groups II, III, and IV were given daily intramuscular doses of CsA for 1 month. The groups were given doses of 5 mg/kg, 7.5 mg/kg, and 10 mg/kg, respectively. Sixty-eight animals were transplanted to get eight viable transplanted animals at 1 month in each CsA group. Laryngeal viability was assessed with both clinical and histological parameters. Groups II, III, and IV had representative clinically viable larynges. The histology varied and had some correlation with CsA dosage. Group II evidenced changes ranging from mild to severe rejection. Group III was more homogeneous with the most severe change being characterized as mild-to-moderate rejection. Group IV was the most uniform with all representative specimens showing only limited infiltration of inflammatory cells with intact mucosa and submucosal glands (mild rejection). None of the CsA groups evidenced the squamous metaplasia characteristic of the control group. CsA can prevent rejection of laryngeal allografts from LBNF-1 donors to Lewis recipients.