A RAPID METHOD TO ANALYSE VON WILLEBRAND FACTOR MULTIMERS

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A RAPID METHOD TO ANALYSE VON
WILLEBRAND FACTOR MULTIMERS Mareli Kelderman,
Muriel Meiring, Philip Badenhorst Haematology and
Cell Biology, University of the Free State
NHLS, Bloemfontein

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Von Willebrand Factor Multimers
separated by electrophoresis
Higher molecular weight
Low molecular weight
REFERENCE Krizek, D.R., Rick, M.E. 2000. A
Rapid Method to Visualize von Willebrand Factor
Multimers by Using Agarose Gel Electrophoresis,
Immunolocalization and Luminographic Detection.
Thrombosis Research, vol. 97, pp. 457-462.
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VON WILLEBRAND FACTOR MULTIMERS

• Plasma proteins that
• promote platelet adhesion to
  sub-endothelium
• form thrombi
• carry FVIII
• protect FVIII

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VON WILLEBRAND DISEASE

• bleeding disorder caused by a deficiency or an
  abnormality of VWF
• VWD patients may have mild, moderate to severe
  bleeding, usually proportionate to degree of VWF
  defect
• correct diagnosis of types and subtypes for
  appropriate therapy
• Type 1 Quantitative
  decreased but normal structure of VWF multimers
• Type 2 Qualitative
  subtype 2A- loss of HMW multimers
  subtype 2B- abnormal affinity for platelets
  subtype 2M- multimers present but
  dysfunctional subtype 2N- reduced
  affinity for FVIII
• Type 3 Absence of VWF

2A 1 1
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LABORATORY DIAGNOSIS 1. Clinical History 2.
Prescribed tests ? Von Willebrand
Antigen (VWFAg) ? Ristocetin Cofactor
(Ricof) ? Factor VIII ? Blood
Grouping ? Multimer Analysis ?
RIPA (Ristocetin induced platelet)
agglutination ? Factor VIII Binding
Assay ? Bleeding Time ? Full
Blood Count (platelet count) ?
Coagulation Tests (PT, PTT)
REFERENCE
Federici, A.B., Castaman, G., Mannucci, P.M.
2002. Guidelines for the diagnosis and
management of von Willebrand disease in Italy.
Haemophilia, vol. 8, pp. 607-621.
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TYPE 1
TYPE 2A TYPE 2A
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METHOD
1. ELECTROPHORESIS
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2. ELECTROTRANSFER
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3. IMMUNOLOCALISATION
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4. DETECTION
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Our first attempts
progression
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..success!
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• CONCLUSION
• The method is reliable.
• The method has advantages such as rapid
  processing, simplicity of gel preparation, high
  sensitivity to low concentrations of VWF and the
  elimination of radioactivity.
• The test promises to be very important and useful
  in the laboratory.
• We need more positive controls.
• However, for the complete diagnosis of subtypes,
  relevant clinical information and additional
  tests are necessary.