Post-transfusion purpura is a rare bleeding disorder
caused by a platelet-specific alloantibody
(usually, anti–human platelet antigen 1a [HPA-1a])
in the recipient. HPA-1a reacts with donor platelets,
destroying them and also the recipient’s
own platelets. The majority of affected patients
are multiparous women who have been sensitized
during pregnancy. Treatments for posttransfusion
purpura
include intravenous immune
(gamma) globulin, glucocorticoids, and plasmapheresis.
High-dose intravenous immune globulin
(2 g per kilogram of body weight administered
over either 2 or 5 days) produces an increased
platelet count in about 85% of patients. Large
numbers of platelet transfusions may be required
to control severe bleeding before there is a response
to intravenous immune globulin. There is
limited evidence that the use of HPA-1a–negative
platelets is more effective than the use of platelets
from random donors.33