What is Ristocetin

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What is Ristocetin?
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History of Ristocetin -1

• 1956-7 Introduced for clinical use
• 1960 Thrombocytopenia and hypofibrinogenemia
  found in rabbits given near therapeutic drug
  levels also noted that ristocetin caused
  macroscopic clumping of platelets, in vitro
  (Gangarosa EJ, et al. Arch Intern Med
  196010583-9.)
• 1960 Drug was discontinued for clinical use
• 1971 Use of ristocetin as a diagnostic tool for
  Von Willebrand Disease (VWD) was born when
  platelets from 2 of 3 patients with VWD failed to
  respond to ristocetin in a Ristocetin-Induced
  Platelet Aggregation (RIPA) test (Howard MA,
  Firkin BG. Thromb Diath Haemorrh 197126362-9.
  Howard MA, et al. Blood 197341687-90.)

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History of Ristocetin - 2

• 1973 Assay described for measuring the
  deficiency of a plasma factor necessary for
  normal platelet function (Weiss HJ, et al. J Clin
  Invest 1973522697-716.)
• Assay based on observation that a log-log
  relationship exists between amount of
  ristocetin-induced platelet aggregation of
  washed, normal platelets and concentration of
  normal plasma present in test system.
• Weiss hypothesized that this cofactor in normal
  plasma was distinct but related to the FVIII
  molecule and called it von Willebrand Factor.
• 1974-5 Assay was enhanced by stabilizing washed
  platelets with paraformaldehyde Allain or
  formalin Macfarlane fixation the latter
  modification is still used today (Ristocetin
  Cofactor assay).
• Ristocetin cofactor activity seems to be
  closely related to some function of the von
  Willebrand factor, but until the nature of this
  factor is determined, the assay should be
  referred to as the ristocetin cofactor assay.
  (Macfarlane DE. Thrombos Diathes Haemorrh
  197534306-8.)