FIG 3.

Type I IFN signaling is dispensable for uptake and killing of S. pneumoniae by macrophages. Adherent PECs were infected with S. pneumoniae D39 at an MOI of 10. (A) Bacteria associating with macrophages were counted at 4, 6, and 8 h after infection as described in Materials and Methods. (B) Phagocytosed bacteria were counted. Non-cell-associated bacteria were removed by washing at 4, 6, and 8 h after infection, and macrophages were cultured for an additional 30 min in the presence of 100 μg/ml of gentamicin. The bacteria in cell lysates were then counted. (C) The viability of phagocytosed bacteria was determined. Gentamicin was added to the cultures 4 h after infection, and the cells were additionally incubated for the indicated times. The bacteria in cell lysates were then counted. All of the experiments were repeated two times, with similar results. Data are presented as the means and standard deviations of triplicate assays.