Intact MCs extracellular traps are required for effective growth inhibition of S pyogenes. (A) Immunostaining with Alexa-red–labeled antibodies against histones of (i) intact MCETs or (ii) disrupted MCETs after treatment with DNAse and myeloperoxidase (bars, 10 μm). (iii) Isotype control antibody (bar, 10 μm). The nucleus of MCs was stained with Dapi (blue). (B) Growth of S pyogenes after coculture with MCs treated with DNAse and MPO to dismantle extracellular trap structures, untreated MCs, or in medium without MCs supplemented with DNAse and MPO. Data are expressed as x-fold increase in bacterial growth with respect to the original inoculum. Each point represents the mean plus or minus SD of 3 independent experiments. *P < .05 by F-test for S pyogenes growth in the presence of untreated HMC-1 cells versus growth of S pyogenes in the presence of DNAse/MPO-treated HMC-1 cells. (C) Analysis of viable (green) versus dead (red) bacteria entrapped in MCETs (i) or grown in medium control (ii) as determined by the LIVE/DEAD BacLight Bacterial Viability assay (bars, 3 μm).