Table 3

Circulating and tissue neutrophil extracellular traps (NETs) during SARS-CoV-2 infection

AuthorPatients NControlRoB
Middleton et al3633 COVID-19 (n=28 hospitalised, n=5 convalescent)17 HD↑ circulating NETs (MPO-DNA complexes) in patients vs HD and convalescent.
NET levels in tracheal aspirate fluid>in plasma samples
Plasma NETs levels=in HD and recovered patients
↑ baseline NETs levels in PMNs isolated from COVID-19 patients
↓ in PMN granularity vs HD
↑ circulating platelet-neutrophil aggregates
High
Veras et al3732 COVID-19 (17 critical and 15 severe)19 HD↑ circulating nets
↑ NETs in the tracheal aspirate from COVID-19 patients
NET levels in tracheal aspirate fluid>in plasma samples
↑ baseline NET levels in PMNs isolated from COVID-19 patients
↑ branch lengths of the released NETs
Unclear
Zuo et al3951 COVID-19
(27 severe, 24 mild)
30 HD↑ cell-free DNA, MPO-DNA complexes, citrullinated histone H3
COVID-19 sera trigger control neutrophils to release NETs
High
Leppkes et al3871 COVID-19None↑ PMNs with low buoyant density, activation pattern (low L-selectin, CD62L) and partial degranulation (increased CEACAM-8, CD66b) resembling low-density granulocytes.
↑ circulating platelet-neutrophil aggregates
Exhausted phenotype with ↓ spontaneous oxidative burst
↑ MPO-DNA complexes and NE-DNA complexes
↑ NE activity in the blood more than 30-fold and 60-fold
High
  • DNA, desoxyribonucleic acid; HD, healthy donor; MPO, myeloperoxidase; NE, neutrophil elastase; NETs, neutrophil extracellular traps; PMNs, polymorphonuclear neutrophils.