A clinicopathologic study of p27(kip1) expression in renal allograft biopsy

Background. P27 (Kip1) is an inhibitor of cyclin-dependent kinases/cyclin complex that keeps mature cells growth-arrested. In IgA nephropathy, a decreased p27(kip1), expression in podocytes has been reported to be related to lesion formation of focal segmental glomerulosclerosis and renal dysfunction. We reviewed the p27kip1 expression in transplanted kidneys. Methods. P27(kip1) expression was examined immunohistochemically in 26 allograft biopsy specimens. Results. P27(kip1) expression was recognized in podocytes. Patients with more than 0.5 g proteinuria showed fewer p27(kip1)-positive cells than those with less than 0.5 g proteinuria. The decreased p27(kip1) expression in podocytes was related to cg and ah of the Banff 97 classification. In the two cases in which p27(kip1) expression was remarkably decreased, elevation of the serum creatinine level was recognized at the time of biopsy, resulting in kidney transplant loss. The histological findings were chronic/sclerosing allograft nephropathy grade II-(b) in both cases. Conclusion. In conclusion, decreased p27(kip1) expression in podocytes suggested a significant role in proteinuria among renal transplant recipients.