Effects of storage on quality and function of acid‐treated platelets with reduced HLA Class I surface expression

Abstract

AbstractBackgroundRefractory patients need to be provided with HLA‐matched platelets (PLTs), which require time‐consuming cross‐matching. Treatment of PLTs with citric acid leads to denaturation of the HLA Class I complexes without significant damage to the PLTs. HLA Class I depleted PLTs could alternatively be used to HLA‐matched PLTs for transfusion. These PLTs have verified normal function up to 4–6 h after acid treatment.Materials and MethodsBuffy coat (BC) PLT concentrates were depleted of HLA Class I complexes by incubation in citric acid. The days after acid‐treatment, surface expression of HLA Class I complexes, CD62P and CD63 were determined by flow cytometry, in addition to viability and mitochondrial membrane potential (MMP). Thromboelastography (TEG) tested PLT functionality.ResultsExpression of HLA Class I complexes was reduced by 70%–75% in acid‐treated PLTs compared to untreated PLTs from day 1 through day 7. Controls and acid‐treated PLTs showed insignificant loss of MMP stored for 4 days. Analysis of the residual PLT activation and viability showed no significant differences for 4 days of storage. However, the residual PLT activation potential and viability were significantly decreased in acid‐treated PLTs and control PLTs after 7 days of storage. Acid treatment caused a significant decrease in the TEG variable, reaction time (R time), for acid‐treated PLTs as compared to control PLTs from days 1 through day 3.ConclusionOur data suggest that extended storage of acid‐treated PLTs is possible and will improve flexibility when planning for transfusion of patients with alloimmune PLT refractoriness caused by anti‐HLA‐antibodies.