TABLE 1.

Effect of anti-IL-10 on the ability of holotoxins to inhibit cytokine release in LT-IIbB-activated THP-1 cells^a

Pretreatment	Amt (pg/ml) of cytokine released (mean ± SD; n = 3)
	TNF-α	IL-8
None	908 ± 132	12,873 ± 1,347
LT-IIa	162 ± 47*	4,912 ± 581*
LT-IIa + anti-IL-10	286 ± 61**	6,502 ± 675**
LT-IIb	124 ± 35*	5,208 ± 740*
LT-IIb + anti-IL-10	261 ± 67**	7,009 ± 803**
CT	102 ± 41*	4,623 ± 419*
CT + anti-IL-10	232 ± 34**	6,149 ± 849**

^aTHP-1 cells were pretreated for 1 h with holotoxins (either LT-IIa, LT-IIb, or CT; all at 2μg/ml) in the absence or presence of anti-IL-10 MAb (10 μg/ml). The cells were then stimulated with LT-IIbB (2 μg/ml). After 16 h, culture supernatants were analyzed by ELISA for TNF-α and IL- 8 release. *, Statistically significant (P < 0.05) inhibition of LT-IIbB-induced cytokine release by holotoxin. **, Statistically significant (P < 0.05) counteraction of the holotoxin inhibitory effect on LT-IIbB-induced cytokine release. Substitution of isotype-matched control for anti-IL- 10 was not statistically different from pretreatment with holotoxin alone (data not shown).