Multiplate® is for research use only in the US and Canada.

Multiplate® RISTOtest is a reagent kit for the quantitative in vitro determination of von Willebrand Factor (vWF)- and glycoprotein Ib (GpIb)-dependent platelet research aggregation studies on the Multiplate® analyzer.

Ristocetin is an antimicrobial substance which forms complexes with vWF (von Willebrand factor). In this complex, vWF changes its conformation in a way that allows it to bind to platelets. The binding of ristocetin-vWF complexes leads to the aggregation and activation of platelets. This activation relies on the binding of vWF to the GPIb receptor and it is inhibited by the action of acetylsalicyclic acid (ASA). This explains the ASA sensitivity of RISTOtest. Complete lack of aggregation in RISTOhigh test can be caused by an absence of GPIb receptors on the platelet surface or by an absence of vWF in the solution.


Reagents, Storage and Stability

  • MP0240: Multiplate® RISTOtest Reagent, Kit, Ristocetin, 3 x 1.0 ml, lyophilized (10 mg/ml). Unopened vials of the RISTOtest reagent must be stored at 2-8°C. The reagent is stable until the expiry date printed on the vial label when stored under these conditions. If reconstituted reagent is not aliquoted into micro test tubes, the original vial should be stored in an upright position. Stable 7 days after reconstitution when stored at 2-8°C, 4 weeks at < -20°C or 24 hours at room temperature after one-time thawing.
  • MP0094: Multiplate® RISTOtest Aliquot Vials, Bag, 100 micro tubes color coded (blue) for for aliquotation.


RISTOtest reagent contains ristocetin. Ristocetin forms a complex with vWF from the sample. This complex binds to the platelet GpIb receptor and triggers platelet activation and aggregation. RISTOtest can be applied in two concentrations: In RISTOhigh test a high concentration of ristocetin (0.77 mg/ml) is applied, which normally induces a strong platelet aggregation. Abolished aggregation in RISTOhigh test can be based on a deficiency of GpIb receptors or vWF. In the RISTOlow test, a lower concentration of ristocetin (0.2 mg/ml) is applied which normally does not induce a strong aggregation response. A higher than expected aggregation in RISTOlow test may indicate an enhanced aggregation tendency of vWF (vWD type IIb). Ongoing research continues to investigate the ristocetin/vWF platelet interaction.