Prevention and management of platelet transfusion refractoriness.

Platelet transfusion refractoriness is a major complication of long-term platelet supportive care. Refractoriness may lead to fatal bleeding complications in thrombocytopenic patients. Major factors involved are factors related to the clinical condition of the patient as well as HLA alloimmunisation. Non-alloimmune factors may occur in up to 80% of the patients. However, platelet transfusion outcome is impaired in only 50% of the patients having these conditions. HLA alloimmunisation has been convincingly reduced by the use of leucocyte-depleted transfusions. UV-B irradiation of platelet transfusions may be alternatively used to reduce HLA alloimmunisation. Despite these measures, patients with a history of pregnancy or non-leucocyte-depleted transfusions form HLA antibodies in a high proportion (up to 50%). HPA antibodies play a minor but relatively important role in patients with HLA antibodies. ABO antibodies may play a role in refractoriness, which can be abolished by transfusion of ABO-identical platelets. Screening for the presence of HLA and/or HPA antibodies is indicated in case of transfusion failure after ABO-identical or HLA-matched platelets. If no alloantibodies are detected, further analysis to define a role of drug- related or autoantibodies is required. In case of HLA and/or HPA alloimmunisation associated with refractoriness, matched platelet transfusions are indicated. In case of non-alloimmune factors associated with increased platelet consumption, increasing the transfusion frequency can be considered. Additional investigations are still necessary to define risk factors for secondary HLA alloimmunisation and refractoriness due to non-immune factors to further decrease the incidence of refractoriness.