Ki-67 proliferative index in kidney biopsies of lupus nephritis patients: a preliminary study

Abstract

Introduction: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that involves multiple organs including the kidneys, skin, joints and serous membranes. Previous studies have shown that elevated Ki-67 indices are correlated with the cellular proliferation and clinical findings in lupus nephritis (LN). Objectives: The aim of this study was to examine the relationship between glomerular, tubular and interstitial expression of Ki-67 in kidney biopsy specimens of different classes of LN and and various clinicopathological features. Patients and Methods: This cross-sectional study was conducted on 16 biopsy-proven LN patients. The diagnosis of LN was based on renal biopsy findings, particularly by immunofluorescence (IF) study. The diagnosis of LN with IF was concluded by the deposition of C1q in association with prominent IgG and C3 deposits and the deposition of IgM and IgA (full-house pattern). The morphologic variables on light microscopy were also examined. In this study, the glomerular (gKi-67), interstitial (iKi-67) and tubular (tKi-67) expressions of Ki-67 were assessed. Results: This study comprised of 16 cases of biopsy-proven LN which were stained for Ki-67 with immunohistochemistry. Of the 16 patients, 13 (81.2%) were females. The mean ± SD of age, quantity of proteinuria and serum creatinine in all patients were 37±11.6 years, 1844±582 mg/d and 1.5±0.93 mg/ dL, respectively. Our study showed that the association between gKi-67, iKi-67, and tKi-67 with age, gender, level of proteinuria and serum creatinine was not significant (P>0.05). The association between Ki-67 with interstitial fibrosis, the number of crescents, and the activity and chronicity percentages was also not significant (P>0.05). Moreover, the relationship of gKi-67 with global versus segmental involvement of the glomeruli was not significant (P>0.05). Furthermore, the correlation of gKi-67 with IgA, IgG, IgM, C3 and C1q deposits was not significant (P>0.05). The association of iKi-67 with age, gender, level of proteinuria and serum creatinine was not significant as well. However, the correlation of iKi-67 with C1q deposits was inversely significant (r=-0.544, P=0.029); however this correlation was not significant with IgA, IgG, IgM and C3 deposits (P>0.05). Conclusion: In this study, the relationship of iKi-67 with C1q deposits suggests that C1q has a significant role in the inflammatory process of LN. Since our study was conducted on a relatively small sample size, it, therefore, requires further investigations on larger samples.