Platelet transfusions and platelet alloimmunization

摘要

Platelet transfusions represent lifesaving therapy for patients who develop severe thrombocytopenia; i.e., platelet counts of <5,000/#mu#l. The majority of patients who develop platelet counts to this level are chronically thrombocytopenic - eitherbecause of disease-induced marrow failure or, alternatively, because of chemo/radiation therapy given to patients with malignant disorders. Because the duration of these patients' thrombocytopenia may be weeks to months, it is important to be able to maintain effective platelet transfusion therapy. The major hazard preventing long-term effective platelet therapy is the development of alloimmune platelet refractoriness which may occur in over 90 percent of transfused patients with aplastic anemia who have no underlying disease or therapy-induced immune incompetence. In cancer patients who are usually being given potentially immunosuppressive chemotherapy while receiving platelet transfusions, immunization rates may be less but still average about 40 percent-60 percent. Thus, identifying techniques to prevent platelet alloimmunization is a high priority for transfusion services. We have used a dog platelet transfusion model to evaluate a variety of methods of preventing platelet alloimmunization. The hypothesis has been that methods of preventing platelet alloimmunization in normal immunocompetent recipient dogs may well be applicable to patients. Approaches to preventing platelet alloimmunization can be categorized into three major strategies: 1) donor selection; 2) recipient immunosuppression; and 3) modification of the donor's platelets prior to transfusion to prevent recipient immune recognition.