Cell culture
THP-1-CWT cells containing the recruitment marker YFP-CWT (recognizing Gram-positive peptidoglycan) (Grosz et al., 2013) were grown in RPMI 1640 medium (Biochrom) with 2mM glutamine, 10% heat-inactivated foetal bovine serum (Sigma), 2% HEPES (Biochrom), 1% penicillin/streptomycin (Gibco) and 1mM sodium pyruvate (SigmaAldrich). Cell viability was determined by trypan blue staining and was at least 90% before all experiments. To induce differentiation, 1 × 106cells/ml were treated with 160nM phorbol-12-myristate-13-acetate (PMA) for 48 h. After differentiation, the cells became adherent to the culture dishes. The day of infection differentiated cells were washed twice with Hank’s Balanced Salt Solution (HBSS) and further incubated with RPMI medium with 10% heat-inactivated fetal bovine serum and 10% human Serum (Sigma) until infection.