Hemolysis assay

Human blood from anonymous healthy donors (obtained from Karolinska University Hospital) was diluted 1:100 in PBS with 0.5 mM DTT and mixed 1:1 with twofold serial dilutions of 10⁸ CFUs of bacteria or 1 μg/ml purified bacterial toxins in 96‐well plates. The MRC‐1 peptides were serially diluted 10‐fold (1–1,000 μM) in PBS and added to the wells prior to addition of blood. The blood was co‐incubated with whole bacteria or purified toxins at 37°C for 1 h, and after 50 min, 0.1% triton X‐100 was added to the positive control wells. Cells were spun down at 400 g for 15 min and the absorbance of the supernatants was measured at 540 nm in a microplate reader. Percentage of lysis compared to the toxin alone was calculated. All samples were assayed in triplicates.