Reduction in adverse transfusion reactions with increased use of washed platelet concentrates in Japan-A retrospective multicenter study.

Plasma removal by washing platelet concentrates (PCs) is effective in preventing adverse reactions to PC transfusions. The Japanese Red Cross Society (JRCS) started releasing washed PCs (WPCs) as a commercially approved blood product in September 2016. This retrospective multicenter study investigated the change in the number of transfused WPCs and the impact on the incidence of adverse reactions to PCs before and after the release. The numbers and types of transfused PCs and the adverse reactions to the PCs for a year before the start of the WPC release and for a year after the release were reported by 27 medical institutes in Japan. Transfusion information for approximately 8% of the amount of PCs supplied in Japan was analyzed during the study period. After the start of WPC release by the JRCS, the number of transfused WPCs doubled. The rate of adverse reactions to PCs decreased significantly (p = 0.0223), from 4.30% before the release to 4.05% after the release. The rates of adverse reactions to unwashed and WPCs were 4.13% and 0.84%, respectively. Allergic adverse reactions were significantly decreased after the release (3.60% before versus 3.37% after). No severe allergic reactions to WPCs were reported. The release of WPCs by the JRCS significantly reduced transfusion-related adverse reactions to PCs in Japan.

Seroprevalence of Trypanosoma cruzi infection among at-risk blood donors in Japan.

BACKGROUND: Chagas disease is caused by Trypanosoma cruzi and is endemic in Latin America. In nonendemic countries, including Japan, Chagas disease is primarily a problem in the context of transfusion transmission. Approximately 250,000 immigrants from Latin America reside in Japan, and many of those individuals serve as active blood donors. This study surveyed the seroprevalence of T. cruzi infection among at-risk blood donors in Japan, defined as those who themselves (or whose mothers) were born (or raised) in Latin America, or those with a travel history to Latin America. STUDY DESIGN AND METHODS: Blood samples were obtained from at-risk donors in two periods, 2004-2012 and 2013-2016. Collected samples were tested for T. cruzi antibodies using both an enzyme-linked immunosorbent assay and a chemiluminescent immunoassay. Samples that tested positive in both assays were additionally tested by polymerase chain reaction, and look-back investigation was conducted when necessary. RESULTS: Of 18,484 samples obtained from 18,076 at-risk donors, 3 (1:6,025, 0.017%) donors showed seroreactivity by enzyme-linked immunosorbent assay and chemiluminescent immunoassay. All antibody-positive donors were born in Latin America. One of them also was positive for T. cruzi DNA. Eleven previous donations from this donor were subjected to look-back investigation, and five recipients were tested. All five recipients tested negative for T. cruzi antibodies. CONCLUSION: Seroprevalence of T. cruzi was 0.017% among at-risk donors in Japan. Transfusion-transmitted infection of Chagas disease has not been confirmed to date. Screening for T. cruzi antibodies by targeting at-risk donors is an appropriate strategy for ensuring blood safety in Japan.

Efficient refolding and immobilization of PMMA-tag-fused single-chain Fv antibodies for sensitive immunological detection on a PMMA plate.

In this study, we investigated the efficient refolding and site-specific immobilization of single-chain variable fragments (scFvs) genetically fused with a poly(methylmethacrylate)-binding peptide (PMMA-tag). According to the results of an aggregation test of a scFv-PM in the presence of 0.5 M urea, aggregation was hardly detectable at a weak-alkaline pH (8.5) with lower concentrations of NaCl. Consequently, more than 93% recovery of the anti-RNase scFv-PM model was attained, when it was refolded by dialysis against 50 mM TAPS (pH8.5). These results suggested that the apparent isoelectric point (pI) of a target scFv was decreased to a great extent by the genetic fusion of a PMMA-tag containing 5 acidic amino acids, and, thus, the solubility of the scFv-PM in its semi-denatured form was considerably improved. We also designed alternative peptide-tags composed of plural aspartic acid residues (D5, D10 and D15-tags) to decrease the apparent pI value of the fusion protein. As a consequence, scFv-D5, scFv-D10 and scFv-D15 were also efficiently refolded with yields of more than 95%. It is noteworthy that even scFv-PS-D15, which had both a positively charged polystyrene-binding peptide (PS-tag) and a negatively charged D15-tag, was serially connected at the C-terminal region of scFvs, and also refolded with a yield of 96.1%. These results clearly indicate that controlling the apparent pI value of scFvs by the fusion of oligo-peptides composed of acidic amino acids at the C-terminus resulted in a high degree of recovery via dialysis refolding. According to the results of a sandwich ELISA using scFv-PMs, scFv-D15 and scFv-PS-D15 as ligands, high antigen-binding signals were detected from both the PMMA and phi-PS plates immobilized with scFv-PMs. Furthermore, the high antigen-binding activity of scFv-PMs was maintained in an adsorption state when it was immobilized on the surface of not only PMMA, but also hydrophilic PS (phi-PS) and polycarbonate (PC). These results strongly suggested that a PMMA-tag introduced at the C-terminus of scFvs preferably recognizes ester and/or carboxyl groups exposed on the surface of plastics. The scFv-PM developed in the present study has advantages such as being a ligand antibody, compared with whole Ab and the conventional PS-tag-fused scFvs (scFv-PS), and, thus, it is considerably useful in a sandwich ELISA as well as in various immuno-detection and immuno-separation systems.

Online reporting system for transfusion-related adverse events to enhance recipient haemovigilance in Japan: a pilot study.

BACKGROUND: A surveillance system for transfusion-related adverse reactions and infectious diseases in Japan was started at a national level in 1993, but current reporting of events in recipients is performed on a voluntary basis. A reporting system which can collect information on all transfusion-related events in recipients is required in Japan. METHODS: We have developed an online reporting system for transfusion-related events and performed a pilot study in 12 hospitals from 2007 to 2010. RESULTS: The overall incidence of adverse events per transfusion bag was 1.47%. Platelet concentrates gave rise to statistically more adverse events (4.16%) than red blood cells (0.66%) and fresh-frozen plasma (0.93%). In addition, we found that the incidence of adverse events varied between hospitals according to their size and patient characteristics. CONCLUSION: This online reporting system is useful for collection and analysis of actual adverse events in recipients of blood transfusions and may contribute to enhancement of the existing surveillance system for recipients in Japan.

Residual risk of transfusion-transmitted hepatitis B virus (HBV) infection caused by blood components derived from donors with occult HBV infection in Japan.

BACKGROUND: Nucleic acid amplification testing (NAT) for hepatitis B virus (HBV) during blood screening has helped to prevent transfusion-transmitted HBV infection (TT-HBV) in Japan. Nevertheless, 4 to 13 TT-HBV infections arise annually. STUDY DESIGN AND METHODS: The Japanese Red Cross (JRC) analyzed repository samples of donated blood for TT-HBV that was suspected through hemovigilance. Blood donations implicated in TT-HBV infections were categorized as either window period (WP) or occult HBV infection (OBI) related. In addition, we analyzed blood from 4742 donors with low antibody to hepatitis B core antigen (anti-HBc) and antibody to hepatitis B surface antigen (anti-HBs) titers using individual-donation NAT (ID-NAT) to investigate the relationship between anti-HBc titer and proportion of viremic donors. RESULTS: Introduction of a more sensitive NAT method for screening minipools of 20 donations increased the OBI detection rate from 3.9 to 15.2 per million, while also the confirmed OBI transmission rate increased from 0.67 to 1.49 per million. By contrast the WP transmission rate decreased from 0.92 to 0.46 per million. Testing repository samples of donations missed by minipools of 20 donations NAT showed that 75 and 85% of TT-HBV that arose from WP and OBI donations, respectively, would have been interdicted by ID-NAT. The ID-NAT trial revealed that 1.94% of donations with low anti-HBc and anti-HBs titers were viremic and that anti-HBc titers and the frequency of viremia did not correlate. CONCLUSIONS: The JRC has elected to achieve maximal safety by discarding all units with low anti-HBc and anti-HBs titers that account for 1.3% of the total donations.

Symptomatic parvovirus B19 infection caused by blood component transfusion.

BACKGROUND: Although a risk of transfusion-transmitted human parvovirus B19V (TT-B19V) infection has been a concern, there have been very few reports of clinically relevant TT-B19V caused by the transfusion of a B19V-containing blood component. It has therefore been a matter of debate whether a universal B19V screening with an appropriate sensitivity is required. STUDY DESIGN AND METHODS: Through the Japanese Red Cross hemovigilance system, clinical reports on possible TT-B19V were collected from 1999 to 2008, during which B19V donor screening (sensitivity, 10(10) IU/mL) was conducted and repository blood samples from donors were available. RESULTS: Eight patients with TT-B19V caused by component transfusion have been identified. Four patients developed sustained anemia and pure red blood cell (RBC) aplasia and one patient developed pancytopenia. The underlying diseases in these five patients were either hematologic malignancy or hemolytic diseases. The viral loads of the responsible components for these cases ranged from 10(3) to 10(8) IU/mL. Two patients who underwent surgical treatment without any hematologic disorder exhibited only moderate symptoms. The B19V DNA sequence identity between a patient and the linked blood donor was confirmed in five of the eight patients. All of the components responsible for the eight cases were positive for anti-B19V immunoglobulin (Ig)M. CONCLUSION: Vulnerability to serious B19V-related hematologic disorders depended on the patient's underlying disease state of an enhanced erythropoiesis, not on the viral load of the component transfused. To prevent clinically relevant TT-B19V, a strategy is suggested in which patients at risk of acquiring RBC aplasia or pancytopenia are targeted.