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Thromb Haemost 1992; 67(03): 320-324
DOI: 10.1055/s-0038-1648440
Original Articles
Schattauer GmbH Stuttgart

Absence of the Largest Platelet-von Willebrand Multimers in a Patient with Lactoferrin Deficiency and a Bleeding Tendency

Robert I Parker
The Hematology Service, Clinical Pathology Department, Clinical Center, Bethesda, MD, USA
,
Laurie P McKeown
The Hematology Service, Clinical Pathology Department, Clinical Center, Bethesda, MD, USA
,
John I Gallin
*   Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
,
Harvey R Gralnick
The Hematology Service, Clinical Pathology Department, Clinical Center, Bethesda, MD, USA
› Author Affiliations
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Publication History

Received 31 May 1991

Accepted after revision 09 October 1991

Publication Date:
03 July 2018 (online)

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Summary

We have studied a young male with lactoferrin deficiency and a bleeding tendency responsive to cryoprecipitate. This child has had increased bleeding following surgical procedures and a variably prolonged template bleeding time. The patient has a normal platelet count, normal in vitro platelet ATP secretion and aggregation in response to a variety of agonists, and normal concentration of plasma-von Willebrand factor ristocetin cofactor activity and antigen. Analysis of plasma-vWf multimers by agarose gel electrophoresis consistently demonstrated a subtle decrease in the largest vWf multimers. In contrast, analysis of the patient’s platelet-vWf revealed normal vWf:Ag, decreased vWf ristocetin cofactor activity, and a striking absence of the high and intermediate size molecular weight vWf multimers. Analysis of surface bound platelet-vWf demonstrated normal amounts on the surface of unstimulated platelets, but after thrombin stimulation the platelet-vWf surface expression did not increase. This lack of increased platelet-vWf surface expression resulted from decreased binding of secreted platelet-vWf to be surface of stimulated platelets. These data suggest that the patient’s bleeding tendency may be related to a defect in his platelet-vWf structure and/or mobilization. This case represents a unique demonstration of an abnormality of platelet-vWf in the presence of normal plasma-vWf, and supports the data indicating an important role for platelet-vWf in primary hemostasis.