NETs assayed by ELISA
The serum level of NETs was measured using the capture ELISA protocol as described previously[16, 26]. Briefly, microtiter plates were first coated with the monoclonal anti-MPO antibody (ab25989, Abcam, UK) and incubated overnight at 4°C. After blocking with 3% skimmed milk, the blood sample diluted at 1:50 was added and incubated for 90 minutes. Then the secondary anti-dsDNA antibody (ab27156, Abcam, UK, 1:2000 dilution) was added into the wells as second antibody. After incubation for 2 hours and washed 4 times, horseradish peroxidase-conjugated rabbit anti-mouse IgG H&L antibody (ab6728, Abcam, UK) was put in. After incubation again, the substrate chromogenic agent was added in turn. 10 minutes later, the reaction suspension solution was mixed and the results was calculated with optical density (OD) at the wavelength of 450nm on the ELIASA (PRA ELX800, Bio Tek, Vermont, USA).