title: IL-1 induction-capacity of defined lipopolysaccharide partial structures.
abstract: Natural and synthetic lipid A as well as natural and synthetic oligosaccharide partial structures of LPS were examined in dose-response experiments to define the minimal structure necessary for IL-1 induction and release in cultures of human mononuclear cells. Wild type LPS (S. abortus equi) and rough mutant LPS was active in minimal-doses of 1 to 100 pg/ml, whereas synthetic heptaacyl and hexaacyl lipid A (Salmonella minnesota and Escherichia coli lipid A, respectively) induced IL-1 in minimal-doses of 100 to 1,000 pg/ml and 10 to 1,000 pg/ml, respectively. Nanogram amounts (0.1 to 10 ng/ml) of synthetic monodephospho partial structures of E. coli lipid A were necessary for IL-1 induction. Synthetic pentaacyl partial structures induced IL-1 very weakly. Synthetic tetraacyl and bisacyl partial structures lacking non-hydroxylated fatty acids were not active. Compared to LPS million-fold higher doses of natural and synthetic 3-deoxy-D-manno-octulosonic acid containing core oligosaccharides were necessary for IL-1 induction. Dose-response investigations with LPS and natural or synthetic partial structures established the following hierarchy in IL-1 induction-capacity: LPS greater than lipid A much greater than lipid A partial structures greater than core oligosaccharides greater than oligoacyl lipid A. Lipid A was shown here to be the portion of LPS mainly responsible for induction of IL-1 activity. The high potency of lipid A in inducing IL-1 release and the failure of the precursor Ia of lipid A to induce IL-1 production and release was also observed measuring intracellular IL-1 activity after freeze-thawing the cells. Levels of IL-1 beta mRNA in extracts of mononuclear cells correlated with biologic activity. In co-incubation experiments, precursor Ia of lipid A produced dose-dependent inhibition of production and release of IL-1 activity induced by lipid A or LPS, but not by Staphylococcus epidermidis or PHA. Incubation of cells with precursor Ia for 1h, followed by a medium change and further incubation of stimulus without precursor Ia of lipid A also resulted in inhibition. We conclude that lipid A is the main portion of LPS responsible for induction of IL-1, and that specific activation- and/or binding-mechanisms are involved in stimulation of cells with LPS and/or lipid A.
authors.affiliation: Department of Immunologie, Forschungsinstitut Borstel, FRG.
authors.forename: H
authors.initials: H
authors.lastname: Loppnow
authors.forename: H
authors.initials: H
authors.lastname: Brade
authors.forename: I
authors.initials: I
authors.lastname: Dürrbaum
authors.forename: C A
authors.initials: CA
authors.lastname: Dinarello
authors.forename: S
authors.initials: S
authors.lastname: Kusumoto
authors.forename: E T
authors.initials: ET
authors.lastname: Rietschel
authors.forename: H D
authors.initials: HD
authors.lastname: Flad
mesh_terms: D000150:Acinetobacter; D001667:Binding, Competitive; D002448:Cell Adhesion; D003593:Cytoplasm / Q000032:analysis; D004926:Escherichia coli; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000302:isolation & purification; D008050:Lipid A / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009844:Oligosaccharides / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology; D012333:RNA, Messenger / Q000302:isolation & purification; D012475:Salmonella; D013329:Structure-Activity Relationship
chemical_list: D007375:Interleukin-1; D008050:Lipid A; D008070:Lipopolysaccharides; D009844:Oligosaccharides; D011498:Protein Precursors; D012333:RNA, Messenger