Tissue factor (TF) expressed on sub-cellular membrane vesicles, so-called plasma microparticles (MPs), has recently emerged as a potential key player in intravascular coagulation activation in various disease states. In this report, we demonstrate significantly increased levels of TF-specific procoagulant activity (PCA) of plasma MPs in five patients presenting with overt disseminated intravascular coagulation (DIC) due to an underlying malignancy, including non-small-cell lung cancer (n = 1), melanoma (n = 1), prostate cancer (n = 2), and acute promyelocytic leukemia (n = 1). Clotting experiments on available tumor cell samples suggested that cancer cells were a potential source of circulating TF-positive MPs at least in three of the five patients. Furthermore, follow-up plasma samples from two surviving patients revealed that response of their malignancies to specific anti-cancer therapy was paralleled by resolution of overt DIC and a significant decline in MP-associated TF PCA. Levels of plasma TF antigen, as assessed by an enzyme-linked immunosorbent assay, were also increased at presentation albeit to a lesser extent compared to MP-associated TF PCA, likely due to insufficient solubilization of the phospholipid-incorporated full-length TF molecule by the detergent. In summary, our findings suggest that MP-associated TF PCA may play an important pathogenic role in the evolution of overt DIC in various types of malignancy.
