A study on the significance of plasma thrombospondin1 in thrombotic thrombocytopenic purpura and the relationship between thrombospondin1 and von Willebrand factor cleaving protease (ADAMTS13)

Abstract

To measure plasma thrombospondin1 (TSP1) in thrombotic thrombocytopenic purpura (TTP) and other diseases such as idiopathic thrombocytopenic purpura (ITP), systemic lupus erythematosus (SLE), myocardial infarction, brain infarction, and malignant tumor et al. and 8 patients after bone marrow transplantation (BMT) were also investigated. Then to study on the relationship between TSP1 and von Willebrand factor cleaving protease (ADAMTS13); and to identify the significance of plasma TSP1 in TTP. TSP1 was measured by a commercial kit and the activity of ADAMTS13 was evaluated by residue collagen binding assay. TSP1 in TTP plasma before plasma exchange or plasma infusion was 6.49 mg/L, and stepping up to 13.02 mg/L after therapy, but still significantly lower than 18.34 mg/L in normal control. While the decrease in different degree of ADAMTS13 activity was observed from 0%-52%, and there were 8 samples whose activity of ADAMTS13 were no more than 10%; the different extent of increase in those patients after therapy was demonstrated to be 2.9%-93.4%, only one patient's ADAMTS13 activity was below 10%. The activity of ADAMTS13 in some ITP and SLE patients were mildly decreased (63% +/- 16% and 70% +/- 14% respectively), TSP1 were also decreased (16 mg/L +/- 8 mg/L). TSP1 in patients of myocardial infarction and brain infarction were increased (24.0 mg/L +/- 2.9 mg/L), while ADAMTS13 activity had no significant change (72% +/- 16%). Same things happened in BMT patients. There was some concordance between the decrease of ADAMTS13 activity and TSP1 in plasma of TTP patients. And the change of TSP1 was restricted to TTP. TSP1 may contribute to the episode of TTP in a still unclear fashions.