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. 2022 Mar 17;13:851497. doi: 10.3389/fimmu.2022.851497

Figure 1.

Figure 1

Critically ill COVID-19 patients have higher plasma neutrophil extracellular trap (NET) levels than those of moderate COVID-19 patients and controls. Plasma NET levels were compared between healthy donors (“controls”, n = 10), moderate [without acute respiratory distress syndrome (ARDS) “non-ARDS”] COVID-19 patients (n = 46), and patients with ARDS (n = 50) admitted to the intensive care unit. Levels of NET markers were as follows: plasma total DNA concentrations [140 ng/ml (124–151) vs. 220 ng/ml (188–271) vs. 428 ng/ml (324–560), p < 0.0001], plasma MPO–DNA levels [0.044 ST (0.012–0.093) vs. 10.15 ST (0.10–0.31) vs. 3.00 (1.38–4.63), p < 0.0001] and plasma H3Cit levels [0.14 (0.088–0.18) vs. 0.17 (0.10–0.30) vs. 0.97 (0.41–1.75), p < 0.0001]. (A) Total DNA concentration (ng/ml). (B) Myeloperoxidase–DNA levels (% standard NETs). (C) Histone H3 citrullinated (absorbance 450 nm). Plasma NET levels were compared between COVID-19 patients treated with prophylactic (n = 71) or therapeutic (n = 25) heparin treatment. (D) Total DNA concentration (ng/ml). (E) Myeloperoxidase–DNA levels (% standard NETs). (F) Histone H3 citrullinated (absorbance 450 nm). Plasma NET levels were compared between COVID-19-related ARDS patients treated with prophylactic (n = 32) or therapeutic (n = 18) heparin treatment. (G) Total DNA concentration (ng/ml). (H) Myeloperoxidase–DNA levels (% standard NETs). (I) Histone H3 citrullinated (absorbance 450 nm). Plasma NET levels were compared between COVID-19 moderate patients treated with prophylactic (n = 39) or therapeutic (n = 7) heparin treatment. (I) Total DNA concentration (ng/ml). (J) Myeloperoxidase–DNA levels (% standard NETs). (K) Histone H3 citrullinated (absorbance 450 nm). Threshold for statistical significance was a p-value of 0.05. *p < 0.05, ***p < 0.0001. NS, statistically non-significant.