A monosaccharide precursor of Escherichia coli lipid A, designated lipid X, which is a diacylglucosamine 1-phosphate with beta-hydroxymyristoyl groups at positions 2 and 3, was shown to have the ability to induce the production of tumor necrosis factor (TNF)-like tumor-cytotoxic factor by a murine macrophage-like cell line, J774.1. This cytotoxic factor was released from J774.1 cells grown in the presence of lipid X and related compounds, and it was assayed as to its lytic activity against [3H]thymidine-labeled L929 cells. Dose-response studies revealed that lipid X induced the production of smaller amounts of the tumor-cytotoxic factor than LPS at low concentrations, but it induced that of considerable amounts at and over 1 microgram/ml. Elimination of 1-phosphate or 3-O-beta-hydroxymyristoyl group from lipid X completely prevented the induction of producing this factor by the macrophages. Therefore, it is suggested that both 1-phosphate and 3-O-beta-hydroxymyristoyl groups are essential for the biologic activity of lipid X, as to the induction of the tumor-cytotoxic factor production in the macrophages.

This content is only available via PDF.
You do not currently have access to this content.