MODULATION OF TISSUE FACTOR ON HUMAN MONOCYTES BY CISPLATIN AND ADRIAMYCIN

Coagulation disorders have been associated with the use of chemotherapeutic drugs. Pharmacological doses of cisplatin and adriamycin directly induced low levels of procoagulant on normal human blood monocytes and on a human myelomonocytic cell line, RC2a. Activity was maximal after 24 h and was not due to cell lysis as increasing drug doses which decreased cell viability were less effective. Procoagulant induction was markedly enhanced in the presence of bacterial lipopolysaccharide (LPS), with as little as 10-100 pg/ml LPS potentiating the cisplatin response by 2-5-fold and more than doubling the adriamycin response. Greater than 90% of the procoagulant activity was membrane-bound tissue factor as indicated by the factor VII-dependent generation of factor Xa by viable cells and by the neutralization of this activity by a monoclonal antibody to tissue factor. Tissue factor antigen was measured simultaneously by immunohistochemical staining and by cell ELISA. Blood monocytes activated with LPS expressed high levels of tissue factor antigen; by contrast, adriamycin and cisplatin did not appear to induce antigen expression, but to enhance the specific activity of that already present. Results suggest that membrane alterations which occur following treatment with DNA/RNA intercalating drugs, may result in a highly active form of monocyte/macrophage tissue factor which may contribute to the complications caused by activated coagulation. Secondary Gram-negative infection or cytokines released by an active immune response to a tumour may contribute to the procoagulant potential of these cytotoxic drugs.