Recognition and inactivation of LPS by lipophorin particles.
Lipophorin is the major lipid carrier in insects, but various observations indicate that lipophorin is also involved in immune reactions. To examine a possible role of lipophorin in defence reactions, we mixed hemolymph plasma from Galleria mellonella with LPS and noticed that lipophorin forms detergent-insoluble aggregates, while most other plasma proteins are not affected. Lipophorin particles isolated by low-density gradient centrifugation retained LPS-induced aggregation properties, which suggested to us that these immune-reactive particles are able to recognise LPS and respond by forming insoluble aggregates. Antibodies against LPS-binding proteins, such as immulectin-2 and beta-1,3-glucan binding protein, cross-reacted with proteins associated with purified lipophorin particles. To examine whether LPS-mediated aggregates inactivate LPS, we added LPS-lipophorin mixtures to purified lipophorin particles and monitored aggregate formation. Under these conditions lipophorin did not form insoluble aggregates, which indicates that lipophorin particles sequester LPS into non-toxic aggregates.
Ma
Gang
G
Insect Molecular Biology, Department of Applied & Molecular Ecology, School of Agriculture and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.
Hay
Douglas
D
Li
Dongmei
D
Asgari
Sassan
S
Schmidt
Otto
O
D000209:Acute-Phase Proteins / Q000276:immunology; D000818:Animals; D002352:Carrier Proteins / Q000276:immunology; D002474:Cell-Free System / Q000276:immunology; D007113:Immunity, Innate / Q000502:physiology*; D008070:Lipopolysaccharides / Q000276:immunology; D008074:Lipoproteins / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics / Q000276:immunology*; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D008070:Lipopolysaccharides; D008074:Lipoproteins; D008562:Membrane Glycoproteins; D000099231:Lipopolysaccharide-Binding Protein; C032830:lipophorin