Comparison of the Levels of Neopterin, CRP, and IL-6 in Patients Infected with and without SARS-CoV-2

Abstract

Background: Neopterin (NP) is a biomarker for activated cellular immunity and is elevated in diseases including viral and bacterial infections, autoimmune diseases, and cancer. However, the clinical assessment of neopterin has not been used for these disorders because the physiological significance of measuring NP is obscure. It would be important to compare the NP profiles with those of other inflammation markers to reveal the significance of NP measurements in pathological states.Methods: Plasma NP, CRP, and IL-6 levels were measured in 46 patients with Coronavirus Disease 2019 (COVID-19) and 13 patients with non-COVID-19 respiratory disorders. The correlations between these markers were analyzed in the COVID-19 and non-COVID-19 patients independently.Results: The NP levels were significantly higher in the COVID-19 patients than in the non-COVID-19 patients, while both CRP and IL-6 were not changed significantly. Among the COVID-19 patients, all three values increased with the severity of symptoms. NP levels were not correlated with CRP or IL-6 levels in COVID-19 patients but were correlated with IL-6 levels in non-COVID-19 patients. The CRP levels were correlated with those of IL-6 in both the COVID-19 and non-COVID-19 patients.Conclusions: The elevation of NP levels was distinct from those of CRP and IL-6 in COVID-19 patients. Our data suggest that NP is produced in different signaling pathways and/or cells than CRP and IL-6. Further study on the signaling pathway to induce NP is expected