Novel Assay Measures Interleukin-6 in Whole Blood Samples

Interleukin 6 (IL-6) is a pleiotropic cytokine produced by various stromal cells and immune system cells, involved in inflammation and infection responses, regeneration process, metabolism regulation, bone homeostasis, and neural functions.

Interleukin 6 assays are useful in early detection of infections and risk stratification of critically ill patients, so an assay with a short turnaround-time and near-patient use is preferred. It is indicated in many diseases such as infection, injury, trauma, stress, neoplasia, post-surgery complications, and chronic inflammatory diseases.

Clinical Laboratorians at the Children’s Hospital of Fudan University (Shanghai, China) included in a study pediatric patients, admitted to the Emergency Department (ED) between April and September 2020 with suspected infection. Blood samples and respiratory tract samples were collected for routine clinical laboratory tests, that is, hematology tests, CRP, PCT, viral antigen, or antibody tests and microbiology culture tests.

The study evaluated the performance of the Pylon IL-6 assay (ET Healthcare, Shanghai, China) based on a cyclic enhanced fluorescent immunoassay performed on a fully automated, benchtop Pylon 3D immuno-analyzer. A total of 100 remnant serum samples from outpatients and ED patients were measured by the Pylon assay and the Elecsys IL-6 assay on a Cobas e 602 (Roche Diagnostics, Rotkreuz, Switzerland). The team carried out imprecision, linearity and comparison studies using serum and plasma samples according to CLSI EP guidelines. The stability of whole blood (WB) samples during storage was assessed.

The investigators reported that the results of serum samples measured by Pylon assays correlated to those measured by Roche assays, as well as to those of matched whole blood samples measured by Pylon assays. IL-6 in whole blood was found stable for ~8 hours at room temperature. Pylon IL-6 results of whole blood samples from 179 pediatric patients with suspected infection showed an AUC of 0.842 in diagnosis of bacterial infection. The within-run CVs and total CVs of Pylon IL-6 assay were determined as 1.8% and 3.0% at 159.3 pg/mL and 3.5% and 4.7% at 8009.9 pg/mL, respectively. The method showed linearity between 1.5 and 42,854 pg/mL. The turnaround time of Pylon IL-6 assay was only an hour when using whole blood samples.

The authors concluded that the new Pylon IL-6 assay demonstrated comparable performance to those assays performed on clinical laboratory instruments. Further, the feature of WB sampling offers advantages in ED or other near-patient settings where turnaround time (TAT) is critical. The study was published on September 20, 2021 in the Journal of Clinical Laboratory Analysis.

Related Links:
Children’s Hospital of Fudan University
ET Healthcare
Roche Diagnostics