Detection of synovial fluid LTF and S100A8 by chemiluminescence immunoassay for the diagnosis of periprosthetic joint infection

Background and Aims: Synovial fluid lactoferrin (LTF) and S100 calcium-binding protein A8 (S100A8) have been considered as potential biomarkers for the diagnosis of periprosthetic joint infection (PJI) through our previous research. However, the detection methods of these two proteins are still immature, so a rapid, accurate and cost-effective testing method is warranted. Materials and Methods: We developed chemiluminescent immunoassays (CLIA) for the automated detection of synovial fluid LTF and S100A8 and assessed the analytical performance for these two methods. In addition, we recruited 86 patients who were suspected of PJI after total joint replacement (TJA) and examined their synovial fluid using CLIA to explore the clinical application value of these methods and the diagnostic efficiency of sy-novial fluid LTF and S100A8 for PJI.Results: Our established CLIA methods have a wide linear range of 20-10,000 ng/mL for LTF detection system and 5-5000 ng/mL for S100A8 detection system. Performance parameters such as precision, specificity, and recovery rate can meet the industry standards. Then, the established methods were used to detect LTF and S100A8 in synovial fluid samples, which showed excellent diagnostic efficiency for PJI, and the areas under ROC curve (AUC) were 0.954 (95 % CI: 0.909-0.999) and 0.958 (95 % CI: 0.918-0.997), respectively.Conclusion: Our established CLIA methods have the advantages of automation, high throughput, low price, and is expected to be widely popularized in clinical applications. Synovial fluid LTF and S100A8 detected through CLIA had efficient diagnostic potentiality for predicting and diagnosing PJI.

Automated summary

Synovial fluid lactoferrin (LTF) and S100 calcium-binding protein A8 (S100A8) have been considered as potential biomarkers for the diagnosis of periprosthetic joint infection (PJI). In this study, we developed chemiluminescent immunoassays (CLIA) for their automated detection and evaluated their analytical performance. The established CLIA methods showed excellent diagnostic efficiency for PJI and have the advantages of automation, high throughput, and low cost, making them promising for clinical applications.