Pathogenic epitope-specific monoclonal antibody-based immunoassay for accurate diagnosis and monitoring of tetranectin in sepsis

Sepsis is a fatal consequence of compromised host immunity due to widespread infection. Its pathogenesis has recently been found to be associated with tetranectin (TN), a monocyte-produced plasma protein with a critical disease-associated epitope, P5-5. To develop a rapid and simple method for early monitoring of the disease in clinical settings, a purified monoclonal antibody (12F1 mAb) with high affinity for the human TN pathogenic epitope P5-5 was produced in this study. The linear range of the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on the mAb to detect TN-P5-5 was 4.8-312 ng/mL, and the half-maximal inhibitory concentration (IC₅₀) was 26.99 ng/mL, with a limit of detection of 2.4 ng/mL. Furthermore, the average recovery of intra- and inter-assay were 103.253 ± 2.803 % and 107.778 ± 7.490 %, respectively. Importantly, the competitive ELISA method established using 12F1 revealed signals corresponding to disease severity in patients with sepsis. Furthermore, the specific in vivo recognition of a pathogenic epitope by mAbs can be extended to therapeutic applications. Collectively, the development of an epitope-specific mAb against disease-associated proteins could be utilized accurately and quantitatively for diagnosing and monitoring diseases in clinical blood samples.