Ki-67 proliferative index in immunoglobulin A nephropathy; A pilot study

Introduction: IgA nephropathy (IgAN) regarded as the main type of primary glomerulonephritis globally. It has a diverse clinical course and unpredictable prognosis. Traditionally, clinical and pathological features are conducted to prognosticate the outcome of the disease. Recently, attention has been directed towards other indices that may have prognostic implications for IgAN progression. The Ki-67 index have been extensively detected as a proliferation marker of malignant cells for several years. Objectives: In this study, we aimed to determine the prognostic impact of Ki-67 expression in IgAN biopsies. Patients and Methods: This cross-sectional study was conducted on 18 biopsy-proven IgAN patients. IgAN was diagnosed by significant IgA deposits and according to the morphologic variables of Oxford (MEST) classification for this disease. The expression of Ki-67 in the glomeruli, interstitium and tubules was described as the intensity percentage of the immunohistochemical staining. Results: In all of the eighteen cases with biopsy-proven IgAN, the mean ± SD of age, degree of proteinuria and serum creatinine were 36.3±17 years, 1600±733 mg/day and 1.2±0.4 mg/dL, respectively. In this study, we found a significant correlation between glomerular Ki-67 immunohistochemical staining and MEST scores (r: 0.780, P< 0.001). We also detected a significant correlation between interstitial Ki-67 staining and MEST scores (r: 0.700, P=0.001). Moreover, Ki-67 immunohistochemical staining of the interstitium had a significant relationship with IgM deposits (r=0.544, P=0.02). Conclusion: In this pilot study, we found that interstitial and glomerular Ki-67 immunohistochemical staining had positive and significant associations with MEST scores. Our data also showed that interstitial Ki-67 staining had a significant relationship with IgM deposits. These preliminary results require further investigation in large-scale studies.