FIG 2.

Naive murine PMNs do not phagocytize B. abortus. (A) Blood from the indicated species was incubated with B. abortus-GFP, S. aureus, or E. coli at an MOI of 20 for 1 h. Blood smears were then fixed and mounted with ProLong Gold Antifade reagent with DAPI. At least 50 PMNs were counted per sample, and the number of intracellular bacteria in each PMN and the proportion of phagocytosis were estimated under fluorescence microscopy. (B) Comparison between C57BL/6 mouse PMNs incubated with B. abortus 2308-RFP at an MOI of 100, human PMNs incubated with B. abortus-GFP at an MOI of 50, and Giemsa staining of C57BL/6 mouse PMNs incubated with latex beads at an MOI of 100, as indicated. Magnifications, ×200 (frame a) and ×400 (frames b and c). Images were cut from the microscope field, contrasted, and saturated using the hue tool to obtain suitable color separation. Similar results were obtained with BALB/c mice.