Cytotoxicity of Bacterial Metabolic Products, including Listeriolysin O, on Leukocyte Targets

Table 5

Survival of PBMC cells of healthy persons treated with different concentrations of B. subtilis supernatants.

Strain		Supernatant concentrations
		1%	2%	3%	4%	5%	10%	20%	30%
MB4	Median	101,3%	101,3%	100,0%	100,0%	100,0%	97,4%	96,1%	94,7%
	P25–P75	100,7–102,0	100,7–101,3	98,0–101,3	100,0–100,7	100,0–100,7	96,7–100,0	94,7–97,4	94,1–95,4
BHI medium	Median	100,0%	98,7%	98,7%	100,0%	100,0%	98,7%	96,1%	96,1%
	P25–P75	99,3–101,3	98,0–101,3	98,0–100,7	98,7–100,7	99,3–100,0	96,7–100,0	96,1–97,4	94,7–96,7
BR1-90	Median	98,7%	100,0%	103,9%	100,0%	100,0%	98,7%	97,4%	90,8%
	P25–P75	97,4–100,7	99,3–100,7	100,7–104,6	99,3–101,3	95,4–100,0	97,4–100,0	96,7–97,4	90,1–92,8
BR1-89	Median	98,7%	101,3%	100,0%	98,7%	98,7%	92,1%	47,4%	7,9%
	P25–P75	98,7–100,0	95,4–102,0	98,7–100,7	98,0–99,3	98,0–98,7	92,1–92,8	35,5–67,1	5,3–30,9
BR1-S	Median	98,7%	97,4%	100,0%	97,4%	94,7%	96,1%	75,0%	35,5%
	P25–P75	98,7–100,7	97,4–100,0	100,0–100,7	90,1–100,0	93,4–98,7	95,4–100,0	57,2–85,5	23,0–55,3

The BHI medium and the supernatant of the MB4 wild-type strain were used as a control sample not containing LLO. The percent given is of living cells in the PI assay for different final IPTG-treated supernatant concentrations of 1–30%, when Jurkat cells were incubated for 30 min at 22^°C (median values, P25–P75, 𝑛=4). The incubation medium contained 4% inactivated NCS. The activities of BR1-89, BR1-90, and BR1-S were not significantly different from each other. Their activities were all significantly higher compared with that of the control supernatant.