Human peripheral blood mononuclear cells require factor X and platelets for expression of prothrombinase activity in response to bacterial lipopolysaccharide.
We investigated whether human peripheral blood mononuclear cells (PBMC) express prothrombinase following stimulation with bacterial lipopolysaccharide (LPS). LPS-stimulated PBMC devoid of contaminating platelets failed to activate prothrombin directly. Addition of platelets did not result in expression of prothrombinase in the absence of factor X whereas the combination of platelets and factor X resulted in strong prothrombinase activity on LPS-activated cells. The induced prothrombinase was dependent on tissue factor, as the activity was completely inhibited by an anti-tissue factor antibody. Our data suggest that platelet/monocyte cooperation is important in the generation of prothrombinase activity in response to endotoxin.
Pejler
G
G
Swedish University of Agricultural Sciences, Department of Veterinary Medical Chemistry, Uppsala. Gunnar.Pejler@vmk.slu.se
Geczy
C L
CL
D000906:Antibodies / Q000494:pharmacology; D001792:Blood Platelets / Q000502:physiology*; D005170:Factor X / Q000502:physiology*; D015951:Factor Xa / Q000096:biosynthesis; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D013925:Thromboplastin / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
D000906:Antibodies; D008070:Lipopolysaccharides; D005170:Factor X; D013925:Thromboplastin; D015951:Factor Xa