Absence of a bleeding tendency in severe acquired von Willebrand's disease. The role of platelet von Willebrand factor in maintaining normal hemostasis.
A 67-year-old male with a prolonged activated partial thromboplastin time (APTT) of 43 seconds (normal, 25-40 seconds) was found to have laboratory features of von Willebrand's disease and IgA myeloma but had a normal bleeding time and no bleeding tendency. Plasma Factor VIII coagulant activity (F.VIII:C) was 80 U/L (0.08 U/mL), Factor VIII antigen (F.VIII:Ag) 70 U/L (0.07 U/mL), and von Willebrand's factor antigen (vWF:Ag) 50 U/L (0.05 U/mL) and ristocetin cofactor (vWF:RiCoF) 10 U/L (0.10 U/mL). The platelet vWF:Ag level was normal, whereas both platelet lysate and plasma vWF high molecular weight multimers were decreased. Patient plasma had no inhibitory effect on either F.VIII:C or vWF:RiCoF. However, when patient plasma was incubated with normal plasma, crossed immunoelectrophoresis for vWF:Ag demonstrated the presence of immune complexes. Infusion of 1-desamino-8-D-arginine vasopressin led to a transient correction of the plasma vWF:Ag multimer pattern. The survival of all components of vWF/F.VIII was decreased, as also occurred after cryoprecipitate. The levels of plasma F.VIII/vWF increased as the IgA values decreased after chemotherapy, whereas the platelet high molecular weight multimers remained decreased. The data suggest that the plasma vWF/F.VIII deficiency results from complexing of the IgA myeloma protein with vWF, resulting in premature clearance of the vWF/F.VIII complex. The absence of clinical bleeding likely results from the combination of a normal platelet vWF:Ag level and persistence of intermediate molecular weight vWF multimers.
Drouin
J
J
Department of Medicine, University of Ottawa, Ontario, Canada.
Lillicrap
D P
DP
Izaguirre
C A
CA
Sutherland
M
M
Windsor
S
S
Benford
K
K
Hoogendorn
H
H
Giles
A R
AR
D000208:Acute Disease; D000368:Aged; D000936:Antigen-Antibody Complex / Q000502:physiology; D001760:Bleeding Time; D005169:Factor VIII / Q000502:physiology; D006474:Hemorrhagic Disorders / Q000097:blood* / Q000150:complications; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D007070:Immunoglobulin A / Q000502:physiology; D008297:Male; D009101:Multiple Myeloma / Q000097:blood / Q000150:complications; D014842:von Willebrand Diseases / Q000097:blood* / Q000150:complications; D014841:von Willebrand Factor / Q000502:physiology*
D000936:Antigen-Antibody Complex; D007070:Immunoglobulin A; D014841:von Willebrand Factor; D005169:Factor VIII