Platelet crossmatch tests using radiolabelled staphylococcal protein A or peroxidase anti-peroxidase in alloimmunized patients

Abstract

Summary. Refractoriness to random‐donor platelets as a result of alloimmunization remains a major problem in long‐term platelet transfusion therapy despite the use of HLA‐matched platelets. We have therefore studied the use of two methods for detection of platelet associated IgG as platelet crossmatch tests for the selection of platelet donors. These methods use radiolabelled staphylococcal protein A (125I‐SPA) and peroxidase anti‐peroxidase (PAP), respectively. One hundred and ten crossmatch tests using 125I‐SPA were performed retrospectively in 18 alloimmunized patients. The results indicated that the predictive value of a positive or a negative test was 87%; the sensitivity was 73% and the specificity was 95%. Results with the PAP test were similar. The HLA types were known for 48 donor‐recipient pairs. With few exceptions, there was a correlation between the results of the platelet crossmatch tests and the effectiveness of platelet transfusion regardless of the degree of HLA match. These results indicate that platelet crossmatch tests may be valuable even when closely HLA matched donors are not available. A large‐scale prospective study is warranted, particularly in highly immunized patients.

Utility of cross‐matched platelet transfusions in patients with hypoproliferative thrombocytopenia: a systematic review

“…Significantly higher count increments were described for cross‐match–compatible versus cross‐match–incompatible PLTs in alloimmunized, refractory patients, and for cross‐match–compatible versus un–cross‐matched PLTs (all but one in refractory individuals). Higher increments for cross‐match–compatible units versus cross‐match–incompatible or un–cross‐matched PLTs were also found in other studies but significance was not reported. In nonrefractory patients, three of five studies showed that cross‐match–compatible PLTs did not result in significantly higher CCIs or success rates with four of the five assays studied .…”

“…Of these, 126 were excluded because they did not fulfill eligibility criteria. The full‐text articles of the remaining 20 citations that met inclusion criteria were retrieved . A search of bibliographies identified an additional 11 references for a total of 31 reports.…”

“…In the majority (24), individuals with various HT states known or likely to be refractory to PLT transfusions comprised the study groups (Table S1). Three of these 24 did not report the prevalence of antibodies to HLA and/or HPA in their cohorts . Seventeen included only participants with demonstrable PLT‐reactive antibodies.…”

“…Eleven studies evaluated the role of HLA matching in cross‐matched PLT transfusion outcomes . Of these, 10 concluded that cross‐match techniques had similar predictive ability across all categories of HLA match (identical or one‐antigen mismatches within or outside cross‐reactive groups) while one concluded that cross‐matching and HLA and ABO matching all had independent predictive value for increment success …”

“…The PRAT assay was found to be associated with transfusion success in the nine studies that reported its use . Three studies observed that the PRAT performed better than LCT, PSIFT, and peroxidase‐antiperoxidase testing …”