Lipopolysaccharide activation of human monocytes mediated by CD14, results in a coordinated synthesis of tissue factor, TNF-α and IL-6

Abstract

We have investigated the role of CD14 in lipopolysaccharide (LPS) stimulation of monocytes to tissue factor (TF) synthesis, tumor necrosis factor (TNF-α) antigen and interleukin-6 (IL-6) antigen release. Elutriation-purified monocytes or peripheral blood mononuclear cells (PBMC) preincubated with a blocking monoclonal antibody against CD14, and monocytes with a reduced expression of CD14 (phosphatidyl inositol specific phospholipase C (PI-PLC) treated monocytes and PBMC isolated from a patient suffering from paroxysmal nocturnal hemoglobinuria, PNH), were stimulated with increasing LPS concentrations. TNF-α antigen and IL-6 antigen were measured in the supernatants, and the cells harvested for measurement of procoagulant activity (PCA) as well as TF, TNF-α and IL-6 mRNA. We conclude that LPS stimulation of monocytes to TF, TNF-α and IL-6 synthesis as well as PCA is totally dependent on CD14 at clinically relevant LPS concentrations (1-50 ng/ml). Moreover, we demonstrate a close correlation between induction of PCA and release of TNF-a and IL-6 antigen indicating a common signalling pathway of induction of these mediators.