Fig 4. 2H7 promotes opsonophagocytic killing by mouse whole blood and human neutrophils.

(A) PBS-washed USA300 (3×10⁴ CFU) was incubated with 200 μl heparinized whole blood collected from BALB/c mice (female, 6-week-old) in the presence of 10 μg/ml 2H7 or isotype control antibody. In addition, blood cells were first lysed in the presence of 0.5% saponin and a control experiment was conducted to examine if 2H7 mediate bacterial aggregations and result in a drop in apparent CFUs. (B) HL60 cells were cultured and differentiated to granulocytes. PBS-washed USA300 (1×10⁴ CFU) was incubated with viable differentiated-HL60 cells (1×10⁵), 4% Guinea pig serum (the cross-reactive antibodies were removed) and 10 μg/ml 2H7 or isotype control antibody. The samples were incubated at 37°C with shaking for 60 minutes. The CFUs of S. aureus were determined by plating on TSA. The relative killing was calculated as the percent difference in CFU between samples at 0 min and 60 min. The data represent the means ± SEM (n = 3). The statistical significance was measured using a two-tailed unpaired t test (**: p<0.01).