Increased expression of p21 (WAF1/CIP1) cyclin-dependent kinase (CDK) inhibitor gene in chronic allograft nephropathy correlates with the number of acute rejection episodes

The p21 (WAF1/CIP1) cyclin-dependent kinase (CDK) inhibitor gene is considered to be the senescence marker in some recent publications. Expression of the gene was evaluated in 14 normal human kidney tissues of different ages and in nine chronically rejected renal allografts. All normal kidneys were negative for p21 expression. Glomerular, tubular and interstitial expression of the marker was detected in 88.9% (P<0.0001) and vascular expression in 66.7% of chronically rejected grafts (P<0.001). No correlation was found between the intensity of p21 expression and recipient age, donor age or number of human leukocyte antigen (HLA) mismatches. The marker was expressed more in grade 3 of chronic allograft nephropathy (CAN) than in grade 2 (P=0.059 for glomerular score). Tubular expression of p21 was correlated with the number of acute rejections: P<0.05 for three vs one and two, and P=0.0046 for three vs no previous acute rejection episodes.