BOF: Transfusion (Platelets)

A forty-five year old man is transfused a pool of platelets due to prolonged platelet recovery after myeloablative chemotherapy with autologous stem cell rescue for multiple myeloma. He subsequently presents to the Emergency Department with widespread ecchymoses and is found to have a platelet count of 4x10⁹/L. Post-transfusion purpura (PTP) is suspected. Which of the following statements is TRUE regarding PTP?

a) Caused by antibody-mediated destruction of donor platelets.

b) Majority of cases are associated with anti HPA-1a antibodies

c) More common following female donation to a male patient.

d) Transfusion of platelets is contraindicated in the acute phase.

e) Usually occurs within 48 hours of platelet transfusion

Answer:

b) Majority of cases are associated with anti HPA-1a antibodies

Explanation:

PTP is a rare complication (1:1,000,000 transfusions) of platelet transfusion, reported 1-5 times per year to SHOT, but much reduced since the advent of universal leucodepletion of blood products. It is caused by a mechanism only partially understood, but involving consumption of recipient platelets due to an immune reaction triggered against the donated platelets due to preformed recipient antibodies to the donor platelets, leading to ‘innocent bystander’ death of recipient platelets, cross reactivity against recipient’s platelets, or stimulation of an autoimmune response against the recipients’s platelets. Hence both donor AND recipient platelets are consumed. There is an association with anti-HPA-1a antibodies, more common in multiparous women or multiply transfused patients. Random donor platelets are essential in the acute phase if there is active bleeding. The condition should be treated with IVIG, plasma exchange or steroids and is often fatal.

Reference:

Padhi P, Parihar GS, Stepp J, Kaplan R. Post-transfusion purpura: a rare and life-threatening aetiology of thrombocytopenia. BMJ Case Reports. 2013;2013:bcr2013008860. doi:10.1136/bcr-2013-008860.