关键词: 肾病综合征, 抗Nephrin抗体, 化学发光法, 细胞间接免疫荧光法, 比较研究, 儿童

Abstract:

Objective To compare the performance differences of the chemiluminescence (CL) method and the cell-based assay (CBA) method in detecting serum anti-Nephrin antibodies in children with nephrotic syndrome (NS). Methods A total of 34 children with nephrotic syndrome (NS) who visited the Pediatric Department from February 2023 to January 2025 were included, along with 18 healthy control children. Serum anti-Nephrin antibodies were detected by CL method and CBA method respectively. The children were grouped according to their urine protein levels and renal pathological types. The differences in positive rates between the groups were compared using the CL method and CBA method. The correlation and consistency between the CL method and CBA method were analyzed. The clinical characteristics of NS children with single positive by CL method and double positive by both CL method and CBA method were compared. Results Among the 34 children with NS, there were 26 boys and 8 girls. The average age was (11.7±3.9) years, and the median disease duration was 5.00 (2.75-9.00) years. There were 19 cases in the urine protein-negative group, 5 cases in the mild to moderate proteinuria group, and 10 cases in the heavy proteinuria group. There were 5 cases of focal segmental glomerulosclerosis (FSGS), 13 cases of minimal change disease (MCD), and 16 cases of minor glomerular abnormalities. The 18 healthy control children tested negative for serum anti-Nephrin antibodies using both the CL method and the CBA method. Among the 34 children with NS, the overall positive rate of CL method was 44.1% (15/34), which was higher than that by the CBA method (11.8%, 4/34), with a statistically significant difference (P=0.003). In NS patients stratified by urinary protein level (negative, mild-to-moderate, heavy), the positive rates of serum anti-Nephrin antibody were 10.5% (2/9), 80% (4/5), 90% (9/10) by CL method and 5.3% (1/19), 0 (0), 30% (3/10) by CBA method, respectively. Among the mild-to-moderate proteinuria and heavy proteinuria groups, the positive rate of the CL method was higher than that of the CBA method, and the difference was statistically significant (P<0.05). When comparing the results grouped by renal pathological types (FSGS, MCD, minor glomerular abnormalities), the positive rates of anti-Nephrin antibodies detected by the CL method were 80.00% (4/5), 46.2% (6/13), and 31.3% (5/16), respectively, while those by the CBA method were 60.00% (3/5), 0 (0), and 6.3% (1/16), respectively. Among them, the positive rate of the CL method in the MCD group was higher than that of the CBA method (P=0.015). Spearman rank correlation analysis showed that the serum anti-Nephrin antibody levels measured by the CL method and the CBA method were significantly positively correlated (r_s=0.57, P<0.001). The consistency analysis of the two detection methods results revealed that the κ value was 0.63 (P<0.001), indicating good consistency. There were no significant differences in the clinical characteristics among NS children with single positive results by the CL method, double positive results by the CL method and the CBA method. Conclusions Both CL method and CBA method can be used to detect anti-Nephrin antibodies and the results are related. However, the CL method has higher sensitivity and can identify a wider range of antibody-positive children, and can be used as a preferred detection and monitoring tool for autoimmune podocyte injury in children with NS.

Key words: nephrotic syndrome, anti-Nephrin antibody, chemiluminescence method, cell-based assay, comparative study, child