TRALI‐risk‐reduction strategies: Japanese approach

Abstract

Transfusion‐related acute lung injury (TRALI) is one of the most serious complications of blood transfusion. We have been gathering information about TRALl in Japan since 1997 through our national haemovigilance system. Recently, we have 20–40 TRALI cases per year (five million bags issued per year). Although TRALI is a rare complication of transfusion, it may become severe and may sometimes be fatal. A substantial number of TRALI cases have been caused by donor HLA or HNA antibodies, which were generated in alloimmunized, i.e. parous females. Considering this mechanism, TRALI mitigation strategies such as the use of male‐only‐plasma have been implemented in many blood centres or countries. Because of the availability of male plasma and the time limit for the production of fresh frozen plasma (FFP), we first tried to prepare FFP‐LR2 derived from 400 ml whole blood only from male donors. FFP‐LR2 accounts for 75% of FFP in Japan. (Six per cent of FFP products are from 200 ml whole blood and 19% from apheresis plasma.) A preliminary project on male‐predominant plasma was started at several core blood centres. To minimize the burden on nurses regarding marking bags collected from males or females, which might lead to serious errors in collection sites, we updated the computer system that allows the staff members in the production department to sort male and female blood automatically. In a month after the system implementation nationwide, we successfully increased the production rate of male plasma for FFP‐LR2 product by up to more than 98%. Regarding FFP‐LR1 derived from 200 ml whole blood, the percentage of female donors is approximately 75%. One of the core blood centres has successfully implemented the same strategy for producing FFP‐LR1, but others have not done so yet. Although male‐only‐plasma strategies achieved good results without any expensive screening tests to reduce TRALI incidence in some countries, the standard measures for other plasma rich blood products such as platelet concentrates or apheresis plasma have not been established yet. There are some measures to consider reducing the risk of TRALI caused by other plasma‐rich products – recruiting only males as apheresis platelet donors, testing a certain number of donors for HLA antibodies, replacing the supernatant of a platelet pool with male plasma and excluding female donors from apheresis donations. Some blood centres adopted some of these measures, but so far there is little evidence for the efficacy of these measures for reducing the risk of TRALI. We have recently conducted research about the relationship between strength of HLA antibodies and TRALI development. On the basis of the results of the research, we can set the cut‐off level in HLA antibody tests, which can reduce the risk of TRALI by eliminating strong HLA antibodies that presumably cause TRALI development if the specificity of an antibody matches the patient’s antigen. Preliminary screening for donor HLA antibodies is ongoing in three core blood centres in Japan, results of which enable us to establish effective and feasible screening strategies for HLA antibodies in the near future.