Department of Pathology, St. John's Medical College and Hospital, Bengaluru, Karnataka, India.
Department of Nephrology, St. John's Medical College and Hospital, Bengaluru, Karnataka, India.
Saudi J Kidney Dis Transpl. 2021 Jan-Feb;32(1):42-48. doi: 10.4103/1319-2442.318547.
In immunoglobulin A (IgA) nephropathy, activation of lectin pathway leads to severe renal damage and more pronounced histological damage. As C4d is a marker of lectin pathway activation, the presence of mesangial C4d positivity will help in identifying those patients at risk. The study was conducted to study the prevalence of mesangial C4d positivity in patients with primary IgA nephropathy and to compare the clinical and histopathological features with C4d-positive and C4d-negative cases. It is a retrospective study conducted for four years. The inclusion criterion was IgA nephropathy with a minimum of four viable glomeruli. Biopsies with >25% of nonsclerotic glomeruli with mesangial positivity will be considered as positive for C4d. Seventy-six patients of IgA nephropathy were included of which mesangial C4d positivity was noted in 33 patients (43%). The mean age was 35 years. The male:female ratio was 2.3:1. The most common presentation was edema (56%) followed by microscopic hematuria (28%). Fifty-four patients were hypertensive. Among the clinical and laboratory parameters, absence of hematuria (P = 0.04) and presence of proteinuria (P = 0.02) showed a significant association with C4d positivity. The histological parameters in Oxford classification which had significant association with C4d positivity were segmental sclerosis (P = 0.01) and tubular atrophy (P = 0.001). Among 45 patients on follow-up with a maximum duration of 51 months, 10 developed end-stage renal disease of which four had C4d expression (0.05%) in the biopsy. Nearly half of IgA nephropathy patients have mesangial C4d positivity. Elevated creatinine with chronicity changes is more common in C4d-positive patients. Hence, C4d can be used as a marker for poor prognosis.
在免疫球蛋白 A（IgA）肾病中，凝集素途径的激活导致严重的肾脏损伤和更明显的组织学损伤。由于 C4d 是凝集素途径激活的标志物，因此系膜 C4d 阳性的存在将有助于确定那些有风险的患者。该研究旨在研究原发性 IgA 肾病患者中系膜 C4d 阳性的患病率，并比较 C4d 阳性和 C4d 阴性病例的临床和组织病理学特征。这是一项为期四年的回顾性研究。纳入标准为至少有 4 个有活力的肾小球的 IgA 肾病。活检中系膜阳性的非硬化性肾小球>25%将被认为 C4d 阳性。纳入了 76 例 IgA 肾病患者，其中 33 例（43%）存在系膜 C4d 阳性。平均年龄为 35 岁。男女比例为 2.3:1。最常见的表现为水肿（56%），其次是镜下血尿（28%）。54 例患者患有高血压。在临床和实验室参数中，血尿缺失（P=0.04）和蛋白尿存在（P=0.02）与 C4d 阳性有显著关联。在与 C4d 阳性有显著关联的 Oxford 分类的组织学参数中，节段性硬化（P=0.01）和肾小管萎缩（P=0.001）。在 45 例接受随访的患者中，随访时间最长为 51 个月，其中 10 例发展为终末期肾病，其中 4 例在活检中表达 C4d（0.05%）。近一半的 IgA 肾病患者存在系膜 C4d 阳性。C4d 阳性患者更常见血肌酐升高和慢性改变。因此，C4d 可作为预后不良的标志物。
