HLA‐selected platelets for platelet refractory patients with HLA antibodies: a single‐center experience

Abstract

BACKGROUND Platelet refractoriness due to HLA immunization represents a problem in transfusion management of thrombocytopenic hematology patients. Refractory patients can be managed by HLA‐selected platelet transfusions, but the optimal matching strategy is debated and how the degree of HLA mismatch influences transfusion outcome is poorly studied. STUDY DESIGN AND METHODS We studied 32 hematology patients who received 142 matched platelet units between 2007 and 2016. Four matching strategies were compared: 1) genomic HLA typing at the two digit level, performed using polymerase chain reaction–sequence‐specific oligonucleotide probing; 2) serologic “eplet score” calculated using HLAMatchmaker; 3) cross‐matching using lymphocyte cytotoxicity; and 4) matching based on donor‐specific antibody (DSA) specificity, determined using Luminex. A 1‐hour corrected count increment (CCI) of more than 7.5 × 109/L was considered a successful response. RESULTS Selection of platelets with either a complete HLA match or an acceptable HLA mismatch based on genomic typing and DSA information, each predicted 86% successful transfusion responses. For HLA‐mismatched transfusions, the eplet score correlated with CCI and the fraction of successful transfusions, but less well compared to DSA matching. Cytotoxic crossmatching was least predictive. For transfusions across one to four DSAs, the antibody reaction strength correlated with the 1‐hour CCI, but many transfusions were successful despite the presence of DSA. CONCLUSION A complete HLA‐A and ‐B match or an acceptable mismatch based on DSA should guide identification of donors. Still, transfusions across DSAs are often successful, emphasizing that the presence of DSA is necessary but not sufficient for platelet clearance.

Efficacy of HLA virtual cross‐matched platelet transfusions for platelet transfusion refractoriness in hematopoietic stem cell transplantation

“…Several articles have reported the effectiveness of HLA‐matched PLTs . Currently, the sensitivity and specificity of virtual cross‐match analysis has undergone remarkable progression.…”

“…17 Several articles have reported the effectiveness of HLAmatched PLTs. 5,[18][19][20][21][22][23][24][25][26] Currently, the sensitivity and specificity of virtual cross-match analysis has undergone remarkable progression. Bub et al reported that the new EpHLA/EpVix method of virtual cross-matching has proved to be effective, feasible, fast, and capable of minimizing efforts on donor identification.…”

“…Previously, Karlström et al also reported that both a complete HLA match and an acceptable HLA mismatch based on genomic typing and donor-specific antibody information predicted 86% successful PLT transfusion responses. 18 Second, because previous studies reported the effect of ABO compatibility on PLT transfusion efficacy, 17,27,28 we assessed the influence of ABO compatibility in the two groups. Because platelets express ABH blood 27 In our study, ABO compatibility was an influential factor in univariate analysis; however, in in multivariate analysis it was not significant, although the number of ABO matched or minor mismatched units in HLA-matched PLT units was slightly more than that in cross-matched PLT units.…”

The effect of serum pretreatment regimens for the detection of HLA class I antibodies in platelet‐refractory patients

“…Patients with immune-based refractoriness respond with higher corrected count increments when HLA-matched or antibody avoidance strategies are used, as compared to corrected count increments achieved after transfusing random single-donor platelets. [16][17][18] This highlights the importance of recognizing HLA antibodies in this patient population. If laboratories with no pretreatment miss antibodies due to the presence of an inhibitor, then platelets selected for these patients may be less effective.…”

“…The clinical importance of a missed specificity is also unknown. Patients with immune‐based refractoriness respond with higher corrected count increments when HLA‐matched or antibody avoidance strategies are used, as compared to corrected count increments achieved after transfusing random single‐donor platelets . This highlights the importance of recognizing HLA antibodies in this patient population.…”