Development of a novel immunoassay for the simple and fast quantitation of neutrophil gelatinase-associated lipocalin using europium(III) chelate microparticles and magnetic beads

Development of a Sandwich Chemiluminescence Immunoassay for the Detection of Intact Procollagen Type I N Propeptide with Magnetic Nanosphere Carrier Technology

The metabolic product of type I collagen synthesis, intact procollagen type I N propeptide (intact PINP), is a potential marker of bone formation and osteoporosis, which is not affected by kidney function. We sought to establish a chemiluminescent immunoassay method for the detection of serum intact PINP with previously prepared paired monoclonal antibodies and to evaluate the diagnostic value of the assay in osteoporosis. Using the capture molecule and monoclonal antibody as detection molecule, a diagnostic reagent was developed to detect intact PINP in serum with magnetic nanosphere carriers by the chemiluminescence method, and its analytical performance in the laboratory was evaluated. Serum intact PINP was measured in 142 healthy people and 115 osteoporosis patients. Results were matched with results of a similar test kit, Roche total PINP Elecsys Chemiluminescent Immunoassay Assay. Compared with the performance of the Roche PINP assay product, our method had higher sensitivity (0.02 ng/mL), wider linear range (0.02-1500 ng/mL), and anti-interference. Serum intact PINP values in osteoporosis patients were significantly higher than in healthy subjects (p < 0.001). Our method had good consistency compared with the Roche PINP assay (r = 0.9794). This chemiluminescence method for detecting serum intact PINP (CLIA-intact PINP) with magnetic nanosphere carrier technology meets the requirements of a clinical testing reagent and is expected to have clinical application after further evaluation and can compete with expensive imported kits on the market.

Establishment of interleukin-18 time-resolved fluorescence immunoassay and its preliminary application in liver disease

Background

To establish a time‐resolved fluorescence immunoassay of interleukin (IL)‐18 (IL‐18‐TRFIA) and detect its concentration in different liver disease serum samples.

Methods

The IL‐18 coating antibody and the Eu³⁺‐labeled detection antibody were used for the IL‐18‐TRFIA to detect serum IL‐18 concentration in patients with liver cancer, hepatitis B, hepatitis C, autoimmune hepatitis, fatty liver disease, and healthy controls. The double‐antibody sandwich method was used and methodological evaluation was performed.

Results

The average intra‐ and inter‐assay coefficient of variation for IL‐18‐TRFIA was 4.80% and 5.90%, respectively. The average recovery rate was 106.19 ± 3.44%. The sensitivity (10.96 pg/mL) was higher than that obtained using the ELISA method (62.5 pg/mL). The detection range was 10.96–1000 pg/mL. IL‐6 and galectin‐3 did not cross‐react with IL‐18‐TRFIA. The serum concentration of IL‐18 was (776.99; 653.48–952.39 pg/mL) in hepatitis C, (911; 775.55–1130.03 pg/mL) in fatty liver, (1048.88; 730.04–1185.10 pg/mL) in liver cancer, and (949.12; 723.70–1160.28 pg/mL) in hepatitis B. Moreover, IL‐18 serum levels were significantly higher in patients than the healthy controls (483.09; 402.52–599.70/mL) (p < 0.0001). Autoimmune hepatitis with a serum IL‐18 concentration of 571.62; 502.47–730.31 pg/mL was not significantly different from the healthy controls (p > 0.05).

Conclusion

We established a highly sensitive IL‐18‐TRFIA method that successfully detected serum IL‐18 concentrations in different liver diseases. Furthermore, IL‐18 serum concentration was higher in patients with liver cancer, hepatitis C, hepatitis B, and fatty liver disease compared to healthy controls.

A Chemiluminescent Immunoassay for Osteocalcin in Human Serum and a Solution to the "Hook Effect"

A chemiluminescent immunoassay for human serum osteocalcin, or bone Gla protein, was established using a double-antibody sandwich model. Examination of the hook effect revealed that it was significantly reduced, and no hook effect was observed at an osteocalcin concentration of 4000 ng/mL. The established method showed good analytical performance and thermal stability. The limit of detection was 0.03 ng/mL. The intra-assay coefficient of variation (CV) was 3.22%-5.64%, the interassay CV was 4.42%-7.25%, and the recovery rate was 93.22%-107.99%. Cross-reactivity (CR) was not observed with bovine, rat, mouse, rabbit, or porcine samples. The developed method showed a good correlation with the N-MID product from Roche. In total, 1069 clinical patient samples were measured using the reagent kit developed in this study.

Fluorescence-based immunoassay for the detection of Xanthomonas oryzae pv. oryzae in rice leaf

The identification of rice bacterial leaf blight disease requires a simple, rapid, highly sensitive, and quantitative approach that can be applied as an early detection monitoring tool in rice health. This paper highlights the development of a turn-off fluorescence-based immunoassay for the early detection of Xanthomonas oryzae pv. oryzae (Xoo), a gram-negative bacterium that causes rice bacterial leaf blight disease. Antibodies against Xoo bacterial cells were produced as specific bio-recognition molecules and the conjugation of these antibodies with graphene quantum dots and gold nanoparticles was performed and characterized, respectively. The combination of both these bio-probes as a fluorescent donor and metal quencher led to changes in the fluorescence signal. The immunoreaction between AntiXoo-GQDs, Xoo cells, and AntiXoo-AuNPs in the immuno-aggregation complex led to the energy transfer in the turn-off fluorescence-based quenching system. The change in fluorescence intensity was proportional to the logarithm of Xoo cells in the range of 10⁰-10⁵ CFU mL^-1. The limit of detection was achieved at 22 CFU mL^-1 and the specificity test against other plant disease pathogens showed high specificity towards Xoo. The detection of Xoo in real plant samples was also performed in this study and demonstrated satisfactory results.

Development of a novel chemiluminescence immunoassay for the detection of procalcitonin

OBJECTIVE

To evaluate the analytical performance of our previously developed chemiluminescence immunoassay (CLIA) kit for the detection of procalcitonin (PCT) and compare with the results obtained using the Vidas B.R.A.H.M.S. PCT™ test (PCT-V).

DESIGN AND METHODS

Our laboratory previously designed a novel CLIA kit and supporting instrument (AE-180) for the detection of PCT. We analyzed the clinical performance of this system, including the imprecision, limit of detection, and linearity of analyses of 305 serum specimens. The results were compared with measurements of the same serum samples obtained with PCT-V.

RESULTS

The limit of detection and blank of our kit were 0.0075 and 0.0039 ng/mL, respectively. The intra- and inter-assay coefficient of variation of the kit were both between 0.8% and 3.9%. The equation of linearity was found to be y = 1.03× + 0.06 (r = 0.99) for concentrations in the range of 0.01-110 ng/mL. The correlation coefficient with the results of PCT-V was 0.995, and the equation obtained for Passing and Bablok regression analysis was 1.061 for our CLIA PCT kit and - 0.003 for PCT-V. Our kit slightly overestimated the concentration according to comparison with PCT-V results.

CONCLUSION

The kit that was previously developed in our laboratory for the measurement of serum PCT concentration using CLIA technology shows excellent performance, just that the functional sensitivity is not as good as the PCT-V; therefore, we suggest that this kit is suitable for clinical use.

Dynamics of Serum Tumor Markers Can Serve as a Prognostic Biomarker for Chinese Advanced Non-small Cell Lung Cancer Patients Treated With Immune Checkpoint Inhibitors

Background: Serum tumor markers carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), cytokeratin 19 fragment (CYFRA21-1) and squamous-cell carcinoma-related antigen (SCC-Ag) are routinely used for monitoring the response to chemotherapy or targeted therapy in advanced-stage non-small cell lung cancer (NSCLC), however their role in immunotherapy remains unclear. The aim of this study was to investigate whether dynamics of these serum markers were associated with the efficacy and prognosis of Chinese late-stage NSCLC patients treated with programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors.

Methods: We initiated a longitudinal prospective study on advanced NSCLC patients treated with PD-1/PD-L1 inhibitors in Chinese PLA general hospital (Beijing, China). Blood samples of baseline and after 6 weeks' treatment were collected. CT scan were used by all patients to evaluate treatment efficacy according to RECIST 1.1. Serum tumor markers levels were measured with an electrochemical luminescence for SCC-Ag and with a chemiluminescent microparticle immunoassay for serum CEA, CA125, and CYFRA21-1. At least 20% decreases of the biomarkers from baseline were considered as meaningful improvements after 6 weeks of treatment with immune checkpoint inhibitors (ICIs). Optimization-based method was used to balance baseline covariates between different groups. Associations between serum tumor biomarker improvements and objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were analyzed.

Results: A total of 308 Chinese patients with advanced NSCLC were enrolled in the study. After balancing baseline covariates, patients with meaningful improvements in <2 out of 4 biomarkers (CEA, CA125, CYFRA21-1, and SCC-Ag) was ended up with lower ORR (0.08 vs. 0.35, p < 0.001), shorten PFS (median: 5.4 vs. 12.5 months, p < 0.001), and OS (median: 11.7 vs. 25.6 months, p < 0.001) in the total population. Subgroup analysis of patients with adenocarcinoma revealed that patients with meaningful improvements in <2 out of 4 biomarkers had significant lower ORR (0.06 vs. 0.36, p < 0.001), shorten PFS (median: 4.1 vs. 11.9 months, p < 0.001), and OS (median: 11.9 vs. 24.2 months, p < 0.001). So as in patients with squamous cell carcinoma, meaningful improvements in at least 2 out of 4 biomarkers were linked to better ORR (0.42 vs. 0.08, p = 0.014), longer PFS (median: 13.1 vs. 5.6 months, p = 0.001), and OS (median: 25.6 vs. 10.9 months, p = 0.06).

Conclusions: The dynamic change of CEA, CA125, CYFRA21-1, and SCC-Ag from baseline have prognostic value for late-stage NSCLC patients treated with PD-1/PD-L1 inhibitors. Decrease of associated biomarkers serum levels were associated with favorable clinical outcomes.