Differentiation between renal allograft rejection and cyclosporine toxicity: a clinicopathological study

The differentiation between cyclosporine nephrotoxicity (CyN) and acute rejection (AR) still remains a matter of intensive research. In a retrospective study over the last 2 years, we assessed the clinical and histopathological data of 43 episodes of renal dysfunction in 39 renal transplant recipients immunosuppressed with cyclosporine (CyA). Ten episodes (23.2%) were identified as AR and 10 (23.2%) as acute CyN; in six cases (13.9%), signs of both AR and CyN were found. Fever (80%), oliguria (50%), and edema (50%) were prominent features in AR, but not in CyN. Renal blood flow was higher in the nephrotoxicity group and for corresponding degree of renal dysfunction. Significant hyperuricemia (greater than 8 mg/dL) was a prominent finding in CyN (80%) and to a lesser extent in AR (20%). The helper to suppressor cell ratio in the peripheral blood remained stable or slightly decreased in all cases with CyN, but increased in 70% of the cases with AR. CyN was associated with significantly higher whole blood CyA levels (P less than 0.005) and there was a positive correlation between plasma creatinine and CyA levels during the nephrotoxicity episodes (P less than 0.02). Diffuse mononuclear cell infiltrate was observed in 90% of the biopsies with AR and only in 20% with CyN (P less than 0.005). Concerning the extent of the tubular lesions, no significant differences were observed between the two groups. In contrast, vascular lesions such as arterial endothelial proliferation (P less than 0.05), hyalinosis (P less than 0.05), and glomerular capillary thrombi (P less than 0.05) were more commonly seen in nephrotoxicity biopsies.(ABSTRACT TRUNCATED AT 250 WORDS)