In Japan, fresh frozen plasma-leukocytes reduced (FFP-LR) must be used within 3 hours after thawing. However, the longer shelf life of thawed FFP-LR makes it applicable for neonatal or critical care settings. Since the level of each coagulation factor does not necessarily reflect physiological coagulation potential, we have conducted a thrombin generation assay in addition to evaluation of coagulant factors for the thawed FFP-LR up to 120 hours. The FVIII level decreased by the largest degree among coagulation factors, however, the level was higher than 0.7 IU/ml (i.e. European standard). FV and FVII levels after 120 hours of storage at 4°C were 0.81±0.18 IU/ml and 0.73±0.12 IU/ml, respectively. The level of fibrinogen was almost unchanged after 120 hours of storage. Thrombin generation was maintained even 120 hours after thawing. These results suggest that thawed FFP-LR can be safely used to treat coagulopathies other than FVIII deficiency for up to 120 hours after thawing.

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Anti-human plasma proteins, especially anti-IgA and anti-haptoglobin, are reported to cause anaphylactic transfusion reactions. To detect anti-plasma proteins effectively, we designed and evaluated a sensitive and specific immunoassay using a Luminex system. Subjected samples were assayed with human plasma proteins (IgA, IgA₁, IgA₂, haptoglobin, α₂-macroglobulin, ceruloplasmin, C4, C9, and albumin) coupled with microspheres and analyzed using the Luminex system. An absorption test was performed for sample serum which had been pre-incubated with pooled human plasma. In the sensitivity test using 2-fold serially diluted anti-IgA and anti-haptoglobin serum, the Luminex assay showed 64 times higher sensitivity than an ELISA. In screening of 242 serum samples derived from non-hemolytic transfusion reaction cases, multi-transfused patients, and healthy donors, 49 were found to be positive for at least one plasma protein using the Luminex assay. Only 2 of these were confirmed positive for anti-IgA₂ and anti-haptoglobin using the absorption test. The other 47 sera were regarded as nonspecific reactions, since their reactivities were not absorbed by pooled human plasma. All 49 Luminex-positive sera were negative on ELISA. Although highly sensitive immunoassays often show nonspecific reactions, conducting a simultaneous absorption test could improve the specificity of the Luminex assay. Therefore, our newly developed Luminex assay is suitable for detecting anti-human plasma proteins in non-hemolytic transfusion reaction cases.

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HTLV-1 antibody testing has been widely used to detect HTLV-1 infection, and high proviral load (PVL) has been reported as one of the risk factors for development of ATL. In this study, we measured the titer of antibodies for HTLV-1 in infected individual using 675 samples from participants enrolled in the Joint Study on Predisposing Factors of ATL Development (JSPFAD). The anti-HTLV-1 antibody titer in particle agglutination assay (PA) rose along with PVL, indicating a correlation between antibody titer and PVL. The titer may represent an easy-to-measure biomarker for the risk of ATL development. In 49 of 604 asymptomatic HTLV-1 carriers (8.1%), PV was not observed; however, antibodies were detected. Furthermore, sequential samples for seven years from identical participants, whose PVLs were around the detectable threshold throughout the donation period, held positive on antibody tests. While all the examined ATL patients in complete remission were negative for PV detection, they continued to show clearly positive for anti-HTLV-1 antibodies. These observations suggest the existence of HTLV-1-infected individuals without appearance of PV in peripheral blood. Antibody testing, in addition to PV detection, is therefore essential for diagnosis of HTLV-1 infection.

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In the survey conducted in 2013, among the 11,015 Japanese institutions receiving blood supply from the Japanese Red Cross Blood Center (JRCBC), the 4,894 institutions, which responded to the questionnaire, were enrolled. Blood management systems such as a unified management system were developed in Japan from 2005 through 2008. However, no significant improvement in efficiency of blood management has been observed since their implementation. In cases of small institutions (less than 300 beds), only 60% were able to implement a system. Nurses authorized by the Japan Society of Transfusion Medicine and Cell Therapy were present in only 32.7% of large institutions (more than 500 beds) and in only 4.7% of all institutions. The modifications regarding the requirements of facilities resulted in a large increase in the number of institutions which were able to establish criteria for obtaining hospital fees for transfusion management. In fact, the acquisition rate of hospital fees increased from 49.7% (2011) to 88.5% (2013) in medium to large institutions (more than 300 beds). Moreover, the introduction of a computer system to transfusion practice has increased gradually over the past 5 years, including implementation of a bar code-based identification system. Compared with fiscal year 2012, the numbers of blood products used according to the number of beds in fiscal year 2013 have changed as follows: Red blood cells and fresh frozen plasma, almost unchanged; platelet products, slightly increased; human albumin products, slightly decreased; intravenous immunoglobulin, increased; autologous blood products, decreased. There was no significant difference in the rates of adherence to the national guidelines of each blood product (77%-80%). Taken together, these observations suggest the importance of promoting the establishment of a blood management system in small institutions and to facilitating the appropriate use of blood products.

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[in Japanese]

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