Suppression of murine macrophage interleukin-1 release by the polysaccharide portion of Haemophilus actinomycetemcomitans lipopolysaccharide.

Lipopolysaccharide (LPS) was extracted from whole cells of Haemophilus actinomycetemcomitans Y4 by the hot phenol-water procedure. LPS was cleaved into its lipid A and polysaccharide moieties by hydrolysis in 1% acetic acid. The major component sugars of the polysaccharide were glucose, heptose, rhamnose, galactose, and fucose. LPS and lipid A from H. actinomycetemcomitans induced the release of interleukin-1 (IL-1) by LPS-responsive C3H/HeN murine peritoneal macrophages and cell line macrophages (P388D1 and J744.1), but not by LPS-nonresponsive C3H/HeJ peritoneal macrophages. The polysaccharide was unable to induce the release of IL-1. It suppressed the IL-1 release from LPS- and lipid A-stimulated macrophages, but not the production of cell-associated and intracellular IL-1. The addition of rhamnose, a sugar component of the polysaccharide, abrogated the inhibitory effect of the polysaccharide on IL-1 release. These results suggest the participation of a lectinlike molecule in IL-1 release.