Macrophages stimulated with interferon-γ kill engulfed <i>S. aureus</i> strains: Newman (A), ATCC 25923 (B), and COL (C) more efficiently than non-stimulated cells.

<p>Cells were stimulated with recombinant human IFNγ overnight at concentrations equivalent to human therapeutic doses (100 U ml⁻¹), and then allowed to phagocytose three different strains of <i>S. aureus</i> for 2 h. Infected cultures were processed as described in the legend for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0001409#pone-0001409-g003" target="_blank">Fig. 3A</a> and live bacteria in the whole cultures (CFU) were enumerated up to 14 days postphagocytosis. Since at the longer timepoints no bacterial growth was detected (CFU = 0) these points were not presented on the graph. The data shown is representative of at least three separate experiments, performed in triplicate, using hMDM derived from different donors. Bars represent mean CFU value ±SD. *, p<0.05; **, p<0.01; ***, p<0.001. NS-not significant.