title: Structural prerequisites for endotoxic activity in the Limulus test as compared to cytokine production in mononuclear cells.
abstract: The structural prerequisites for lipopolysaccharide (LPS) and its partial structures for the activation of the Limulus clotting cascade (Limulus amebocyte lysate [LAL] test) are described and compared with the corresponding requirements for the activation of human immune cells such as mononuclear cells. A necessary, but not sufficient, structural motif for this is the presence of the 4(')-phosphate-diglucosamine backbone recognition structure ('epitope') in lipid A. High activity is only expressed by assemblies of endotoxins, but this is largely independent of the type of supramolecular aggregate structure. A particular conformation of the epitope within the lipid A assembly must be present, which is influenced by addition of further saccharide units to the lipid A moiety, but also reacts slightly to the acylation pattern. In contrast, the cytokine production of human immune cells induced by LPS sensitively depends on the type of its aggregate structure. In the case of a hexa-acylated bisphosphorylated lipid A structure, high activity is only observed with cubic inverted aggregates. Furthermore, addition of antimicrobial agents (such as polymyxin B) leads to a nearly complete inhibition of cytokine production, whereas the reduction in the Limulus assay is much lower. These data are important since a reliable determination of endotoxin concentrations, in particular with respect to its ability to elicit severe infections, is of high interest.
authors: Forschungszentrum Borstel, Borstel, Germany.
authors: T
authors: T
authors: Gutsmann
authors: J
authors: J
authors: Howe
authors: U
authors: U
authors: Zähringer
authors: P
authors: P
authors: Garidel
authors: A B
authors: AB
authors: Schromm
authors: M H J
authors: MH
authors: Koch
authors: Y
authors: Y
authors: Fujimoto
authors: K
authors: K
authors: Fukase
authors: I
authors: I
authors: Moriyon
authors: G
authors: G
authors: Martínez-de-Tejada
authors: K
authors: K
authors: Brandenburg
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004731:Endotoxins / Q000097:blood / Q000737:chemistry; D005944:Glucosamine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D006737:Horseshoe Crabs; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008033:Limulus Test / Q000379:methods*; D008050:Lipid A / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D008213:Lymphocyte Activation; D011237:Predictive Value of Tests; D055503:Protein Multimerization; D012107:Research Design
chemical_list: D016207:Cytokines; D004731:Endotoxins; D008050:Lipid A; D005944:Glucosamine