Increased D-dimer levels correlate with binding of activated protein C, but not tissue factor expression, on peripheral blood monocytes in cancer patients

Monocyte tissue factor expression Is supposed to play an important role in the hypercoagulability of blood in cancer patients. The relation between co agulation parameters and the expression of monocyte membrane proteins invol ved in hemostasis or monocyte activation was studied in 21 patients with a disseminated malignancy and 21 age- and sex-matched healthy controls, In th e cancer patient group no increase of monocyte tissue factor expression was found (8.4% vs. 7.8%; P = 0.83), but a significant increase of monocyte-bo und activated protein C (APC) (28.8% vs. 13.4%; P = 0.009) and monocyte CD1 6 expression (34.5% vs. 27.0%; P = 0.007) was observed. There was also a si gnificant increase of D-dimers (2.0 vs. 0.2 mu g/ml; P = 0.001), a decrease of antithrombin (83.5% vs. 102.0%; P = 0.004), but no increase of TAT comp lexes (1.7 vs. 1.5 mu g/l; P = 0.38) or factor VII, (68.5% vs. 15.0%; P = 0 .52). The increase of D-dimers was significantly correlated with the monocy te APC (R = 0.60; P = 0.005), but not with monocyte tissue factor levels (R = -0.22; P = 0.35) or TAT complexes (R = 0.12; P = 0.60). These results re flect a local rather than systemic thrombin and fibrin formation. It is sug gested that the APC formed locally enters the circulation and binds to peri pheral blood monocytes. APC bound on monocytes is known to inhibit monocyte cytokine production and might therefore be involved in regulatory response s of monocytes in cancer patients. Am. J. Hematol. 64:282-286, 2000. (C) 20 00 Wiley-Liss, Inc.