Neutrophil Markers as Predictors of COVID-19 Severity at Hospital Admission: A Cross-sectional Study.

COVID-19 is capable of undermining self-tolerance in a host's immune system and triggering autoimmunity by hyper-activating the innate and adaptive immune systems, which has not investigated in Iranian society until now. In the innate immune system neutrophils are the predominant immune cells that protect the human body against invaders. Here, we sought to explore 2 important variables related to neutrophil: DNA complexes with myeloperoxidase (MPO-DNA) as a reliable indicator of neutrophil extracellular traps (NETs) by MPO-DNA complex evaluation using a sandwich ELISA and the underlying role of IL-8 in (NETs) formation during COVID-19 infection. According to our results, in 103 COVID-19 patients, neutrophil-to-lymphocyte ratio (NLR) was significantly higher in ICU patients (14.62±11.81) compared to non-ICU patients (3.16±3.33). Elevated IL-8 levels were observed in COVID-19 patients, particularly in ICU patients. MPO-DNA levels, indicating NETosis, were significantly higher in COVID-19 patients and strongly correlated with neutrophil counts (r=0.472). Thus, our studies suggest that neutrophils count, IL-8, and MPO-DNA can be used as powerful biomarkers in diagnosing COVID-19 severity. patients with severe COVID-19 infection are prone to heart disease because most of them develop excessive NET formation. Additionally, In COVID-19 patients, a higher MPO-DNA level may increase the risk of developing heart disease too.