Nat. Med. 16, 1018–1023 (2010); published online 5 September 2010; retracted 15 June 2011

In the version of this article initially published, we reported that CXCL8 could efficiently induce neutrophil extracellular trap (NET) formation in vitro. When we followed up on the effect of recombinant CXCL8 (IL-8) on NET formation by comparing different cell culture conditions and extending our studies to neutrophils obtained from a larger number of healthy blood donors, we found that the CXCL8 effect was donor dependent and was less robust than we previously thought. In investigating the underlying factors, we observed that the CXCL8 effect that we initially observed was favored by our cell culture conditions (CXCL8-72aa (CXCL8 that is 72 amino acids in length) at 100 nM; RPMI-1640 medium; absence of albumin, buffers or serum; supplementation with L-glutamine; and precoating of culture plates with poly-D-lysine 30–70 kDa). We had initially chosen these conditions because we felt that they resembled the pulmonary microenvironment. On the basis of our recent observations, however, we conclude that these culture conditions are unstable and allow nonspecific neutrophil activation and autocrine/paracrine CXCL8 release.

In light of these results, we revise our conclusions to state that the effect of recombinant CXCL8 on NET formation is less efficient than we previously reported, donor dependent and less robust compared to the effect of phorbol 12-myristate 13-acetate. Thus, we wish to retract the paper.

We did not use this in vitro methodology in the ex vivo and in vivo studies of human and mouse cystic fibrosis lung disease. Accordingly, we continue to endorse our NETosis studies in the context of cystic fibrosis lung disease.