Comparison of HLA antibody identification methods for the selection of platelet products for HLA-mediated platelet refractory patients.

In an ineffective transfusion context, solid-phase immunoassays using the Luminex platform for the detection and characterization of HLA antibodies are currently used to select HLA-compatible platelet products. A new HLA antibody identification method, the HISTO SPOT® HLA AB test (BAG Health care GmbH, Lich, Germany), based on the detection of antibodies directed against a recombinant single antigen (SA) by colored spots detected by HISTO MATCH HLA AB module software, runs fully automated on the MR.SPOT®. The aim of this study was to compare the ability of the HISTO SPOT HLA AB and C1qScreen™ (C1q SAB) assays with that of the Labscreen single antigen class I (OL SAB) assay to detect anti-HLA class I antibodies in 56 serum samples from 54 platelet refractory acute myeloid leukemia patients who received HLA mismatch platelet concentrates at a single oncohematology center. In total, 1414 class I specificities, 433 HLA-A and 981 HLA-B, were detected by the OL SAB test. The mean fluorescence intensity (MFI) was >5000 for 874 antigens and <5000 for 655 antigens. The HISTO SPOT® HLA AB and C1q SAB tests identified 85% and 79% of OL SA-detected antigens with an MFI >5000, respectively, but did not identify 34% and 44% of OL SAB-detected antigens, highlighting the lower sensitivity of these techniques. Interestingly, the donor-specific antibodies (DSAs) identified by the HISTO SPOT® HLA AB and C1q SAB assays reacted against HLA mismatch platelet concentrates with the same specificity (86%) and positive predictive (77%) value as in the OL SAB test when the MFI threshold was >2000 for DSA detection. Although the HISTO SPOT® HLA AB test is less sensitive than the OL SAB test, this test could be used for the selection of HLA-compatible platelet products.

Therapeutic efficacy of platelet transfusion treated with amotosalen/UVA pathogen inactivation technology (INTERCEPTTM Blood System) in acute myeloid leukemia patients undergoing chemotherapy with curative intent: a single center experience.

BACKGROUND: The INTERCEPTTM Blood System (Intercept Blood System, Cerus Europe BV, Amersfoort, the Netherlands) has been used to reduce or inactivate pathogen load in platelet concentrates in France for three years. MATERIALS AND METHODS: After comparing the transfusion efficiency between pathogen-reduced platelets (PR_PLT) and untreated platelet products (U_PLT), our single-center observational study assessed the effectiveness of PR_PLT for the prevention of bleeding and for therapeutic treatment of WHO grade 2 bleeding in 176 patients undergoing chemotherapy with curative intent for acute myeloid leukemia (AML). The main endpoints were the 24-hour (h) corrected count increment (24h_CCI) after each transfusion, and time to next transfusion. RESULTS: Whereas the transfused doses tended to be higher in the PR_PLT group compared to U_PLT, there was a significant difference in intertransfusion interval (ITI) and 24h_CCI. In prophylactic transfusions, PR_PLT transfusions of >0.65×1011/10 kg, regardless of the age of the product (day 2 to day 5), resulted in a 24h_CCI similar to that of the untreated platelet product; this meant the patient could be transfused at least every 48h. In contrast, most PR_PLT transfusions of <0.55×1011/10 kg did not achieve a transfusion interval of 48h. In the context of WHO grade 2 bleeding, PR_PLT transfusions >0.65×1011/10 kg and storage of less than 4 days seems more effective in stopping bleeding. DISCUSSION: These results, which must be confirmed by prospective studies, indicate the need for vigilance regarding the quantity and quality of PR_PLT products used to treat patients at risk of bleeding crisis. Future prospective studies are needed to confirm these findings.