A Comprehensive Comparison between H&E/PAS Staining and CD3/PAS Mixed Staining Evaluating the Difference in Banff Scoring of Kidney Transplantation Biopsy Specimens

Abstract

Introduction The Banff classification is widely used for diagnosing kidney transplant rejection, but challenges persist in accurately identifying certain histological features. This study aimed to evaluate the efficacy of PAS/CD3 mixed staining in improving the diagnosis and grading of T-cell mediated rejection (TCMR) compared to conventional staining methods. Methods Paraffin-embedded tissue samples from 106 kidney transplant recipients were examined using H&E, PAS, and PAS/CD3 mixed staining. Two pathologists independently evaluated Tubulitis, interstitial inflammation, and intimal arteritis according to Banff classification criteria. Concordance between staining methods were assessed using weighted Kappa statistics. Results High agreement was observed between conventional and mixed staining methods for Tubulitis (85, P-value<0.001), interstitial inflammation (87, P-value<0.001), and intimal arteritis (100, P-value<0.001). Notably, 31 of cases initially scored as t0 in routine staining were upgraded to t1, and about 25 of t1 cases were upgraded to t2 when using CD3/PAS slides. Conclusions While PAS/CD3 mixed staining showed high concordance with conventional methods, it demonstrated potential benefits in detecting mild Tubulitis and interstitial inflammation. The upgraded scores in a significant portion of t0 and t1 cases suggest that mixed staining could enhance the detection of subtle histological changes. However, the clinical significance of these findings remains to be determined, and further research is warranted to fully elucidate the role of mixed staining in kidney transplant biopsy evaluation. Copyright © 2026 Urology Research Center (URC), Tehran University of Medical Sciences.