Endotoxin-neutralizing capacity of soluble CD14.
Luminol-enhanced chemiluminescence was used to determine the effect of soluble CD14 (sCD14) on the endotoxin-inducible generation of reactive oxygen species in human monocytes. It was necessary to mediate lipopolysaccharide (LPS) monocyte-activating capability by serum factors (LPS-binding proteins). sCD14 reduced LPS-inducible monocyte activation in a dose-dependent manner, even in the case of CD14- monocytes, obtained from a patient with paroxysmal nocturnal haemoglobinuria. These monocytes could be activated by opsonized LPS via other receptors. Using anti-mouse Ig-coated microbeads, it was demonstrated in FACS analysis that sCD14 mediates the binding of a mouse monoclonal anti-CD14 antibody (RoMo 1) to a complex of LPS/FITC (fluoroisothiocyanate) and a LPS-binding protein. The release of sCD14 from cultured monocytes was measured using LPS, TNF alpha (tumour necrosis factor), IL1, 4 and 6 (interleukin-1, -4 and -6) and IFN gamma (interferon-gamma) as stimulators. Addition of LPS and TNF alpha led to a dose-dependent increase in sCD14-levels in the culture supernatant, whereas IL1, IL6 and IFN gamma had no significant effect. IL4 dose-dependently depressed spontaneous sCD14 release. It is possible that elevated sCD14-serum levels in polytraumatized patients indicate a natural protective mechanism against excessive monocyte mediator production. Therefore, sCD14 may be a new therapeutic concept in endotoxic shock prevention.
Schütt
C
C
Dept. Medical Immunology, Ernst-Moritz-Arndt-University Greifswald, Germany.
Schilling
T
T
Grunwald
U
U
Schönfeld
W
W
Krüger
C
C
D015703:Antigens, CD / Q000276:immunology*; D015214:Antigens, Differentiation, Myelomonocytic / Q000276:immunology*; D004731:Endotoxins / Q000037:antagonists & inhibitors* / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides / Q000276:immunology; D008163:Luminescent Measurements; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012772:Shock, Septic / Q000276:immunology / Q000517:prevention & control; D012995:Solubility
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D004731:Endotoxins; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D010100:Oxygen