Serum level of interleukin-6, interleukin-17A, and interferon-α in hospitalized COVID-19 patients and their clinical correlation: A hospital-based case–control study from North-East India

BACKGROUND AND OBJECTIVES: Dysregulation in the homeostasis of the cytokine pool induces severity in COVID-19 disease, which may result in poor clinical outcomes in severely ill patients. The main objective of this study was to evaluate serum interleukin-6 (IL-6), IL-17A, and interferon-α (IFN-α) in hospitalized COVID-19 patients and its association with the disease severity and clinical outcome. MATERIALS AND METHODS: Fifty-one hospitalized COVID-19 patients and 30 age- and sex-matched healthy volunteers were enrolled in this study. Serum IL-6, IL-17A, and IFN-α were quantified by enzyme-linked immunosorbent assay-based method. Receiver operating characteristic curve (ROC) analysis was performed for the cytokines. RESULTS: Serum IL-6, IL-17A, and IFN-α were significantly higher in COVID-19 patients than healthy control volunteers. Across severity groups, serum IL-6 was significantly higher in the severe group, whereas IFN-α was significantly higher in the mild–moderate group. Serum IL-6 was significantly higher in the deceased group compared to the recovered group. ROC analysis suggests that serum IL-6 can be used as a diagnostic and prognostic marker for severity and clinical outcome, respectively. CONCLUSION: Elevated levels of serum IL-6, IL-17A, and IFN-α in COVID-19 patients indicate cytokine dysregulation following severe acute respiratory syndrome coronavirus 2 infection. Elevated serum IL-6 was associated with disease severity and poor clinical outcome. Elevated IFN-α in mild–moderate group compared to the severe group signifies the antiviral effect of IFN-α may help in limiting disease severity in COVID-19 disease. Our data suggest that IL-6 can be used as a diagnostic and prognostic marker for disease severity and clinical outcome, respectively.