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

Table 6

Survival of Jurkat cells treated with different concentrations of B. subtilis supernatants.

Strain		Supernatant concentrations
		1%	2%	3%	4%	5%	10%	20%	30%
MB4	Median	101,4%	109,3%	108,6%	109,3%	111,4%	111,4%	119,3%	121,4%
	P25–P75	96,4–106,4	108,2–110,0	106,8–112,5	104,3–113,6	109,6–115,0	109,6–114,3	117,9–120,4	118,9–123,6
BHI medium	Median	105,0%	104,3%	100,7%	105,0%	101,4%	100,7%	100,7%	96,4%
	P25–P75	104,3–106,8	100,7–106,4	98,9–102,1	102,9–107,5	100,7–102,5	99,6–102,5	99,3–101,4	94,6–97,5
BR1-90	Median	105,6%	104,9%	102,8%	98,6%	93,7%	73,2%	40,8%	8,5%
	P25–P75	102,–109,2	101,4–108,5	96,8–107,0	90,1–104,2	83,1–102,5	62,0–89,4	34,5–44,0	8,1–8,5
BR1-89	Median	98,1%	93,1%	83,8%	68,1%	32,5%	4,4%	0,0%	0,0%
	P25–P75	94,1–101,6	91,3–95,6	78,1–88,8	64,4– 68,8	23,4–38,4	3,4–5,3	0,0–0,3	0,0–0,3
BR1-S	Median	100,0%	98,7%	96,8%	94,3%	78,5%	25,9%	1,9%	1,3%
	P25–P75	99,1–101,3	97,2–100,6	96,2–98,1	88,0–96,8	76,3–85,4	17,4–35,1	1,3–2,5	0,9–1,6

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 supernatant concentrations of 1–30%, when PBMC were incubated for 30 min at 22^°C (median values, P25–P75, 𝑛=3). The incubation medium contained 4% inactivated NCS. The activity of BR1-90 was not significantly different from that of the control supernatant of the MB4 strain; however, supernatant activities of BR1-89 and BR1-S were significantly higher.