RESUMO
Previous publications have described thrombotic events with unclear causes in individuals infected with the human immunodeficiency virus (HIV). We stratified the cases of 52 individuals infected with HIV by degree of immunosuppression and the presence of complicating illnesses. Plasma from these individuals was screened for abnormalities that might predispose to thromboses. We found statistically significant differences between patients with CD4 counts < 200/mm3 and those whose CD4 counts were > 400/mm3 in the following: d-dimers, functional protein C, antigenic protein C, total protein S antigen, free protein S antigen, C4b-binding protein (C4b-BP), and von Willebrand antigen (vWD). Free protein S correlated inversely with C4b-BP; vWD directly with total protein S; and protein C inversely with d-dimers. D-dimers were significantly elevated only in immunosuppressed patients with complicating neoplastic/inflammatory disease. We propose that low-grade disseminated intravascular coagulopathy in severely immunosuppressed individuals with HIV and infectious, inflammatory, or neoplastic complications is responsible for depressed protein C, which, together with elevations in total protein S and vWD (markers of endothelial injury), indicates a thrombotic predisposition.