How is alloimmunized refractoriness to platelet transfusions treated?

Updated: Sep 08, 2017
  • Author: Douglas Blackall, MD, MPH; Chief Editor: Michael A Kaliner, MD  more...
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Avoiding platelet transfusions as much as possible is important in alloimmunized patients. Prophylactic transfusions are not recommended. Measures to minimize the likelihood and extent of bleeding (eg, rapid treatment of infection; avoidance of invasive procedures; correction of coagulation deficiencies, anemia, and renal insufficiency; use of antifibrinolytic agents) should be used extensively.

After diagnosing alloimmune platelet refractoriness, use the sequence of measures that follows, initiating each subsequent intervention if the previous one fails.

  • Rule out nonimmune, autoimmune, and drug-related causes of platelet refractoriness and treat accordingly. Providing immune-compatible platelets is unlikely to be effective in the presence of nonimmune causes of refractoriness.

  • Consider alternatives to platelet transfusion to control bleeding, including the use of antifibrinolytic agents such as alpha-aminocaproic acid or activated recombinant factor VIIa. [14]

  • Transfuse ABO-compatible fresh (aged < 48 h) platelet concentrates. ABO-matched and fresher platelets are associated with higher posttransfusion platelet increments than mismatched and older (age >3 d) platelets.

  • Transfuse with platelets from blood relatives. Obtaining platelets from blood relatives is worthwhile because the chance of matching 2 or more HLA and platelet antigens is high (resulting in good recovery), and relatives are often willing to donate frequently. Irradiation of blood products from relatives is mandatory to prevent transfusion-associated graft-versus-host disease.

  • Select HLA-matched platelets. Perform HLA typing of patients who will receive multiple transfusions before they become pancytopenic (eg, bone marrow transplant recipients). Matching for both private (ie, HLA-A, HLA-B) and public (ie, cross-reacting groups) antigens is best achieved by computerized selection of donors, based on the results of the PRA assay.

  • Select crossmatched platelets. Crossmatch-compatible platelets can significantly improve platelet recovery in approximately 50% of patients who are refractory to random-donor platelets. Selecting crossmatched platelets is especially indicated for patients with high PRA levels or those who do not respond to HLA-matched platelets.

  • The use of HPA1a/5b-negative platelets has been successful in cases of posttransfusion purpura and neonatal platelet alloimmunization. These antigens are involved in most (95%) of these cases, but they account for no more than 10-20% of immune refractoriness to platelet transfusions.

  • Pretreat with IVIG before transfusion. IVIG pretreatment can result in successful increments after platelet transfusion in patients who are alloimmunized. Success rates vary and depend on the degree of alloimmunization. IVIG does not reduce the level of alloantibodies but may decrease platelet-associated immunoglobulins and possibly interferes with platelet destruction mechanisms. IVIG is more effective in improving short-term (1-6 h) recovery of platelets than longer term platelet survival (>24 h).

  • Use high-dose platelet transfusion. Empirical use of high doses of random platelet units (eg, 1 apheresis unit tid or 2-3 apheresis units before invasive procedures) may result in a lower overall titer of the effecting antibody(ies), overwhelming the mononuclear-phagocyte system, and increasing the survival of transfused platelets.

  • Attempt large-volume plasmapheresis. Plasmapheresis (eg, 2 plasma volumes for 1-3 d) before bone marrow transplantation results in beneficial responses in most patients who are alloimmunized to platelets. Perfusion of the plasma through a staphylococcal protein A column is an experimental treatment that has met with some success.

  • Consider administering immunosuppressive drugs. While steroids are not effective, isolated reports suggest that immunosuppressive therapy may be beneficial. As examples, the use of vincristine and cyclosporin A has been successful but require 2-3 weeks to take effect.

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