Methods for the selection of platelet products for alloimmune‐refractory patients

Abstract

The ability to efficiently and accurately diagnose the cause(s) of platelet (PLT) refractoriness is paramount in providing effective PLT products for transfusion. Recent advances in methods for detecting and identifying alloantibodies against human leukocyte antigens (HLAs) and human PLT antigens, combined with accurate molecular techniques for HLA typing, have provided a framework for the development of clinical algorithms to support such patients. Alloantibodies may be detected and/or identified by several methods, including complement-dependent cytotoxicity, enzyme-linked immunosorbent assays (ELISA), and microbead-based assays using Luminex or flow cytometry. The primary difference in these assays is the sensitivity of detection and the range of antibody specificities that may be reliably identified. Direct PLT cross-matching to identify compatible PLTs can be accomplished by several methods, including solid-phase red cell adherence, modified antigen capture ELISA, and flow cytometry. A survey of blood centers and laboratories providing transfusion support has identified the heterogeneity of testing options available, areas of concern and need for improvement, and common obstacles in providing appropriate and timely support to immune-refractory PLT patients. Depending on the testing methods and the pool of HLA-typed PLT donors available, there are numerous options for developing suitable algorithms to provide effective support to immune-refractory PLT patients.

Peripartum management of HLA alloimmune platelet refractoriness

“…In general, the provision of HLA‐compatible PLTs can be achieved by matching PLT concentrate donor and recipient HLA‐A and ‐B antigens. Alternatively, donor units that have HLA antigens against which the intended recipient has antibody can be avoided (i.e., antigen‐negative), and PLT crossmatching can be performed . With the exception of patients with infrequent HLA‐A and ‐B types, we generally are able to provide fully matched PLTs (at HLA‐A and ‐B) with the help of our blood vendor.…”

Genotyping Applications for Transplantation and Transfusion Management: The Emory Experience

“…Two recent reviews have detailed practical approaches for the selection of platelet products for patients with alloimmune platelet transfusion refractoriness. 30,31 …”

Ethical Questions about Platelet Transfusions at the End of Life

“…(It is worth noting, however, that not all cases of platelet refractoriness are immune mediated.) Platelet refractoriness is typically defined as three consecutive transfusions with less than expected (based on platelet dose and estimated body surface area) rise in platelet counts at one-hour post transfusion [3]. Not surprisingly, the theoretical risk of alloimmunization rises with the number of transfusions (both packed red cells and platelets).…”

“…Testing for compatibility is performed in vitro and evaluates both the patient's own HLA antigens and the reactivity of the patient's plasma against other class I antigens found in the general population. Blood products are either HLA-compatible (i.e., the recipient plasma does not harbor HLA antibodies that react to the HLA antigens on the donor platelets) or HLA-identical (i.e., the recipient and donor HLA antigens are identical) [3]. In patients for whom it is difficult to find HLA-compatible platelets, cross-matched platelets-those that do not react in vitro with the recipient's serum irrespective of antigen or antibody status-can be a suitable alternative.…”