Liposomes (at a concentration of 9 nM) containing either LLO or heat killed LLO (LLO was inactivated by incubation at 70uC for 10 minutes) were prepared as previously described [31] . Liposomes were incubated with BMDMs on coverslips at a 1:10,000 dilution (ratio of liposome-containing media to cell media) and rinsed with 37uC fresh cell media after three minutes of incubation with the BMDMs. The coverslips containing cells were fixed as described above. At least 300 liposomes were counted per time point and the experiment was repeated three independent times.