The procoagulant activity of human granulocytes, lymphocytes and monocytes stimulated by endotoxin. Coagulation and electron microscopic studies.

Leukocytes from donor blood were separated by ficoll/Urovison density centrifugation into granulocytes, lymphocytes and monocytes. The cell fractions were suspended in a culture medium to which endotoxin of Salmonella enteritidis was added at a final concentration of 10 microgram/ml. Endotoxin-stimulated monocytes developed a very high tissue factor (thromboplastin) activity while in granulocytes an only negligible amount of tissue factor activity was detectable. The tissue factor activity measured in the preparation of the lymphocytes can be explained by contamination with monocytes. Eelectron microscopic studies showed the lysosomes of all monocytes to be enlarged and activated. Only a fraction of the granulocytes appeared degranulated with prominent vacuoles containing inclusion bodies. Possibly the high tissue factor activity of the monocytes triggers the development of the disseminated intravascular coagulation in the Shwartzman phenomenon.