Ristocetin induced platelet agglutination
Encyclopedia
The ristocetin induced platelet aggregation (RIPA) is an in vitro assay for von Willebrand factor
activity used to diagnose von Willebrand disease
. It has the benefit over the ristocetin cofactor activity in that it can diagnose type 2B vWD and Bernard-Soulier syndrome
.
In an unknown fashion, the antibiotic ristocetin
causes von Willebrand factor to bind the platelet receptor glycoprotein Ib
(GpIb), so when ristocetin is added to normal blood, it causes agglutination. In von Willebrand disease, where von Willebrand factor is absent or defective, abnormal agglutination occurs:
Von Willebrand factor
von Willebrand factor is a blood glycoprotein involved in hemostasis. It is deficient or defective in von Willebrand disease and is involved in a large number of other diseases, including thrombotic thrombocytopenic purpura, Heyde's syndrome, and possibly hemolytic-uremic syndrome...
activity used to diagnose von Willebrand disease
Von Willebrand disease
von Willebrand disease is the most common hereditary coagulation abnormality described in humans, although it can also be acquired as a result of other medical conditions. It arises from a qualitative or quantitative deficiency of von Willebrand factor , a multimeric protein that is required for...
. It has the benefit over the ristocetin cofactor activity in that it can diagnose type 2B vWD and Bernard-Soulier syndrome
Bernard-Soulier syndrome
Bernard–Soulier syndrome , also called hemorrhagiparous thrombocytic dystrophy, is a rare autosomal recessive coagulopathy that causes a deficiency of glycoprotein Ib , the receptor for von Willebrand factor, which is important in clot formation.The incidence is estimated to be less than 1 in 1...
.
In an unknown fashion, the antibiotic ristocetin
Ristocetin
Ristocetin is an antibiotic, obtained from Amycolatopsis lurida, previously used to treat staphylococcal infections. It is no longer used clinically because it caused thrombocytopenia and platelet agglutination. It is now used solely to assay those functions in vitro in the diagnosis of conditions...
causes von Willebrand factor to bind the platelet receptor glycoprotein Ib
Glycoprotein Ib
Glycoprotein Ib , also known as CD42,is a component of the GPIb-V-IX complex on platelets. The GPIb-V-IX complex binds von Willebrand factor, allowing platelet adhesion and platelet plug formation at sites of vascular injury....
(GpIb), so when ristocetin is added to normal blood, it causes agglutination. In von Willebrand disease, where von Willebrand factor is absent or defective, abnormal agglutination occurs:
- In type 1 vWD: hypoactive agglutination occurs
- In type 2A vWD: hypoactive agglutination occurs
- In type 2B vWD: hyperactive agglutination occurs
- In type 2M vWD: hypoactive agglutination occurs activity
- In type 2N vWD: normal agglutination occurs
- In type 3 vWD: no agglutination occurs