Continuous Platelet Transfusion As a Potential Desensitization Regimen in HLA Class I Alloimmune-Mediated Platelet Refractoriness

Background:The development of HLA antibodies is responsible for 4-8% of platelet transfusion refractoriness (PTR). The presence of HLA antibodies is a clinical complication that is generally managed by the selection of products that are negative for the antigens cognate to the patient's antibodies. Often, this selection is facilitated by targeted recruitment of donors with known HLA types. However, for very broadly HLA-alloimmunized patients, compatible products may be exceedingly scarce or completely unavailable, precluding the ability to consistently provide products the patient will likely increment to and benefit from. Here we describe a case of a patient with severe aplastic anemia (platelet count chronically <1 K/uL) and platelet transfusion refractoriness secondary to broad HLA-alloimmunization (98% PRA). HLA compatible products were unavailable due to the patient's rare HLA type and breadth of antibodies, and attempts at procuring compatible products via multiple national agency searches were unsuccessful. Thus, the patient could only be supplied with HLA incompatible products, which yielded insufficient post-transfusion platelet corrected-count increments (CCI). Her course was eventually complicated by multifocal intracranial hemorrhages, necessitating ICU admission with aggressive platelet transfusion support, immune-targeting therapy consisting of IVIg, and aminocaproic acid and recombinant activated factor VIIa.