FIG. 3.

Supernatant TNF-α ELISA. Human PBMC (2 × 10⁵, in triplicate) were stimulated for 24 h in RPMI-10% FCS with 1 or 10 ng of purified LPS O26:B6 or LPS O22/ml, purified from E. coli WAF108, WAF270, or WAH540, and the supernatants were assayed for TNF-α. Error bars indicate significant errors of the means. There were no differences in TNF-α secretion between transformants when the cells were stimulated for less time (i.e., 6 to 12 h).