TABLE 4.

Effect of IFN-γ treatment on B. suis-infected VD3-THP-1 cells^a

Cell treatment	%b of:
	Apoptotic VD3-THP-1 cells	Infected VD3-THP-1 cells	Apoptotic cells in the infected-cell population
Medium	4 ± 1
IFN-γ	66 ± 10
GFP-B. suis infection	3 ± 2	14 ± 2	1 ± 1
GFP-B. suis infection + IFN-γ	23 ± 5	16 ± 3	15 ± 4

^aVD3-THP-1 cells were infected (or not) with opsonized GFP-B. suis in eight-chamber culture slides (as described in Materials and Methods) and then cultured (or not) with 10,000 U of IFN-γ per ml after gentamicin had killed extracellular bacteria. Forty-eight hours later for each condition, the percentage of apoptotic cells (red fluorescence), infected cells (green fluorescence), or apoptotic cells in the infected-cell population (green plus red fluorescence) was determined by fluorescence microscopy with phycoerythrin-labeled annexin V as described in the legend to Fig. 5. 

^bPercentages were determined by analyzing at least 800 cells; values are means and standard deviations from seven different experiments.