Tissue factor expression by PBMC in response to homocysteine concentration–response curve.

Procoagulant activity of PBMC was assayed after 4 hour-incubation with various concentrations (10 μmol/L to 500 μmol/L) of homocysteine, with buffer or with LPS (100 ng/mL) as a positive control. (A) Clotting times in the 1-stage assay are shown for 10 different healthy volunteers. Data are shown as mean ± SEM of triplicate samples for each subject. (B) Thromboplastin activity, calculated by reference to a standard curve performed with each experiment and normalized to the number of monocytes in each sample. Results shown are geometric mean ± SEM of the results for 9 of the subjects shown in the top panel, after exclusion of the outlier.