Development of magnetic particle-based chemiluminescence immunoassay for measurement of human procalcitonin in serum

Highlights

• A chemiluminescent immunoassay for procalcitonin detection was newly developed.

• The detection limit of our assay could reach to 0.03 μg/L.

• A good correlation was observed between our assay and VIDAS BRAHMS PCT.

Abstract

Background

Serum procalcitonin (PCT) has been recognized as a primary biomarker in bacterial infections, and monitoring its concentration could help to evaluate the prognosis of sepsis and guide the antibiotic administration. We aimed to establish a fast and accurate immunoassay for PCT quantitation.

Methods

Our newly developed monoclonal antibodies (mAbs) against human PCT were preliminarily evaluated by enzyme-linked immunosorbent assay and then used to develop a chemiluminescence enzyme immunoassay (CLEIA). The proposed CLEIA was assessed in analytical performance and applied to measurement of serum PCT.

Results

mAb 2D3 and mAb 8F6 were selected as capture and detection antibody respectively, due to the highest sensitivity for PCT detection with no cross reaction to calcitonin gene-related peptides. The proposed CLEIA based on mAb pair of 2D3/8F6-AP was characterized for a working range from 0.03 to 100 μg/L. An excellent correlation was observed between our proposed assay and the VIDAS BRAHMS PCT assay (r: 0.9825).

Conclusion

Our newly developed mAbs and CLEIA can serve as important diagnostic tools for measurement of human PCT in serum.

Introduction

Procalcitonin (PCT) is propeptide of calcitonin, with a relative molecular mass of about 13kD and consists of 116 amino acids. The levels of serum PCT have been found very low or undetectable in normal persons, usually less than 0.1 μg/L, but markedly elevated in patients with severe systemic inflammation, infection, and sepsis (Meisner, 2002; Becker et al., 2004). A high serum PCT level commonly occurs in patients with bacterial infection (Whicher et al., 2001), and it has been claimed as a safe biomarker to discriminate bacterial and viral infectious disease (Tujula et al., 2019). Studies also suggested that serum PCT levels are closely related to the occurrence and process of sepsis, and the quantitative measurement of serum PCT could help to evaluate the prognosis of sepsis and guide the antibiotic initiation and termination (Georgopoulou et al., 2011; Soni et al., 2013; Schuetz et al., 2010; Sager et al., 2017; Lipinska-Gediga et al., 2016). PCT assay has been increasingly recognized as an important diagnostic and monitoring tool in clinical practice (Becker et al., 2008; Prkno et al., 2013). PCT measurement could increase diagnostic certainty of pneumonia in patients with acute heart failure (Maisel et al., 2012). Using a PCT-algorithm to guide antibiotic use in sepsis and hospitalized lower respiratory tract infection patients is expected to generate cost-savings to the hospital and lower rates of antibiotic resistance and C. difficile infections (Mewes et al., 2019).

The methods for quantitative measurement of serum PCT mainly include fluorescent, chemiluminescent and electrochemiluminescent immunoassay (Schneider and Lam, 2007). The results from recent reports indicated a superior sensitivity of the newly-developed ARCHITECT BRAHMS PCT (based on a chemiluminescent microparticle immunoassay) over the VIDAS BRAHMS PCT (based on an enzyme-linked fluorescent immunoassay) (Aydemir et al., 2019; Wang et al., 2019). The present study aimed to develop high-affinity and high-specificity monoclonal antibodies (mAbs) against human PCT, and then establish a magnetic particle-based chemiluminescence enzyme immunoassay (CLEIA) with a local automated platform for fast and accurate PCT quantitation. To evaluate the application prospects of developed mAbs and CLEIA, the values of serum PCT obtained by our proposed CLEIA were compared with the clinical values obtained by VIDAS PCT assay.