Procoagulant activity of endotoxin or tumor necrosis factor activated monocytes is enhanced by IgG from patients with lupus anticoagulant.

The effect of lupus anticoagulant (LA) positive plasma on the expression of human monocyte procoagulant activity (PCA) was studied. LA positive plasma were able to enhance the endotoxin or TNF alpha induced monocyte associated PCA. The monocyte PCA had the characteristic of tissue factor activity (factor VII, factor X dependence). The enhancement of monocyte PCA could be confirmed using purified LA positive IgG. The stimulating effect was supported by the F(ab')2 fragments.