Abstract
Background: Krebs von den Lungen-6 (KL-6) has been proposed as a disease severity marker of COVID-19. All research articles reported the KL-6 assay detected through Fujirebio reagents by Lumipulse G600/G1200 instrument. In the present study, KL-6 assay was analysed through Tosoh AIA-360 and compared with analytical results by Lumipulse G600 in a population of COVID-19 patients. Materials and methods: Sixty-four patients (median age, IQR 67 (58–76) years), all hospitalized for COVID-19 interstitial pneumonia at Siena COVID Unit. KL-6 was measured by two methods, chemiluminescence enzyme immunoassay (CLEIA) and fluorescent enzyme immunoassay (FEIA) method by Lumipulse G600 II and AIA 360 systems, respectively. Results: KL-6 concentrations evaluated by Lumipulse G600II were significantly higher in severe than those in non-severe patients (p < 0.0001) as well as evaluating by AIA360 (p < 0.0001). Receiver operating curve (ROC) curve analysis showed that KL-6 concentrations, by Lumipuse G600II, distinguished severe from non-severe COVID-19 patients with an area under the curve (AUC) of 99.8% and the best cut-off value was 448 U/mL. AUROC between severe and non-severe COVID-19 patients using T0 KL-6 concentrations by AIA360 was 97.4% and the best cut-off value was 398 U/mL. According to T0 KL-6 concentrations in COVID-19 patients, Bland–Altman difference analysis revealed a mean bias of 78 ± 174.8; while using T1 KL-6 concentrations in COVID-19 patients, Bland–Altman difference analysis revealed a mean bias of 48 ± 126 (95% limits of agreement −199–295) between the Lumipulse G600 II and the AIA360 systems. Conclusions: In conclusion, our study demonstrated that CLEIA and FEIA methods for serum KL-6 detection are comparable and reliable. KL-6 was confirmed as an easily detectable and effective biomarker to identify severe COVID-19 patients.
Highlights
Krebs von den Lungen-6 (KL-6) is a one of the transmembrane mucins in the lung expressed by injured or regenerating pneumocytes type II [1,2]
The pathogenesis of COVID-19 is unclear, though it is postulated that elevated serum concentrations of proinflammatory cytokines and oxidative stress mediators contribute to lung injury, facilitating the onset of an acute respiratory syndrome
KL-6 assay was analysed by the fluorescent enzyme immunoassay (FEIA) method through Tosoh AIA-360 and compared with analytical results by Lumipulse G600 in a population of COVID-19 patients
Summary
Krebs von den Lungen-6 (KL-6) is a one of the transmembrane mucins in the lung expressed by injured or regenerating pneumocytes type II [1,2]. Since outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, KL-6 has been proposed as a disease severity marker [20,21,22,23]. The pathogenesis of COVID-19 (as the lung disease caused by SARS-CoV-2 is defined) is unclear, though it is postulated that elevated serum concentrations of proinflammatory cytokines and oxidative stress mediators contribute to lung injury, facilitating the onset of an acute respiratory syndrome (similar to ARDS). We further serially evaluated serum KL-6 behaviour in a population of COVID-19 hospitalized patients during follow-up, in order to investigate its potential role in predicting clinical course of disease [21]. KL-6 assay was analysed by the fluorescent enzyme immunoassay (FEIA) method through Tosoh AIA-360 and compared with analytical results by Lumipulse G600 in a population of COVID-19 patients
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