TABLE 1.

TNF-α production by THP-1 cells activated by LPS in the presence of supernatants of B. suis mutants^a

Expt no.	TNF-α concn (pg/ml)
	Medium	WT supernatant	Δomp25 B. suis supernatant	Δomp25-omp25 B. suis supernatant
1	2,580 ± 230	1,320 ± 90*	1,940 ± 212†	1,120 ± 110‡
2	658 ± 120	90 ± 12*	600 ± 100†	300 ± 30‡
3	790 ± 95	142 ± 21*	700 ± 50†	342 ± 20‡

^aVD3-differentiated THP-1 cells were preincubated for 30 min in complete medium supplemented with a 1/10 dilution of supernatant from WT B. suis, Δomp25 B. suis, or Δomp25-omp25 B. suis or in medium alone. They were then stimulated by addition of E. coli LPS at 100 ng/ml. Seven hours later, the TNF-α concentration in each supernatant was measured by ELISA. Three experiments were performed, and each value shown represents the mean ± SD of four different determinations in one experiment. Paired Student t tests showed that the differences between values bearing the symbols * and † (P = 0.0031) and between those bearing the symbols † and ‡ (P = 0.01) are significant, while those between values bearing the symbols ∗ and ‡ (P = 0.65) are not significant.