Predictive Role and Clinical Value of Serum Cytokines in COVID-19

Cytokines and chemokines are clinically relevant for severity prediction and treatment of COVID-19 caused by SARS-CoV-2. We aimed to demonstrate the potential cytokines for severity prediction in the five days after symptom onset and describe the importance of serum cytokine levels for patients with different disease severity.

Hospitalized COVID-19 patients and healthy control participants were recruited, and serial sera were collected from COVID-19 patients. Thirteen cytokines, including interleukin (IL) 1β, interferon (IFN) α2, IFN- γ, tumor necrosis factor (TNF) α, monocyte chemoattractant protein (MCP-1/CCL2), IL-6, IL-8 (CXCL8), IL-10, IL-12p70, IL-17A, IL-18, IL-23, and IL-33, were studied by bead-based multiplex assay by flow cytometry. Data regarding routine laboratory test results (leucocyte count, neutrophil count, lymphocyte count, platelet count, hemoglobin, liver transaminases, C-reactive protein [CRP], procalcitonin, and creatinine) were collected.

We demonstrated that COVID-19 patients had elevated serum levels of IFN-α2, TNF-α, MCP-1/CCL2, IL-6, IL-8, IL-18, IL-33 compared to healthy participants. Elevated levels of CRP and decreased lymphocyte count were observed in the critical disease group. Longitudinal analysis revealed a statistically significant increase in IL-6, IL-18, and MCP-1 serum levels of critical patients compared to healthy controls.

MCP-1, IL-6, and IL-18 were found to be the best predictors of critical COVID-19 disease, and MCP-1 has the highest level of predictive performance.