Mismatches of minor histocompatibility antigens (mHas) between HLA-identical stem cell donors and recipients are known as a major risk factor for graft-versus-host disease (GVHD). We determined alleles of 9mHas for 40 patients who had undergone stem cell transplantation from HLA-identical donors and investigated the association of their mismatches with relapse rate and GVHD. We observed a tendency toward a higher incidence of GVHD and lower relapse rate in patients with at least one or more incompatibilities of mHas than in patients without incompatibilities. In particular, relapse rate was significantly lower in a group of patients grafted from HLA-identical sibling donors with mHa-incompatibilities (p=0.05). In addition, no relapse was observed in at least one or more mHa-incompatible patients who developed GVHD. We conclude that mHas contribute to the development of the graft-versus-leukemia effect and may potentiate the graft-versus-leukemia effect in incompatible patients who develop GVHD.

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We experienced a case of anti-f antibodies in a patient with a history of blood transfusion. The patient was a 54-year-old Japanese man with an alcoholic psychosis who received three red blood cell transfusions for the treatment of anemia from November 22, 2001 to January 18, 2002. During this period, his serum was screened twice, and no immune antibodies were detected. Prior to a subsequent fourth transfusion, anti-f antibodies were detected in his serum on a third screening. The titers were ×2 by the Bromelin method, and ×4 by the Coombs method, showing a dosage effect which is characteristic of Rh blood groups. At the same time, his direct antiglobulin test was positive, but there was no evidence of clinical hemolysis. After detection he received a single transfusion of compatible blood with good effect. This case emphasizes the importance of regular antibody screening in patients receiving multiple transfusions of red blood cells.

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The Gov alloantigen system is carried by the platelet membrane protein CD109. The Gov antigen has a polymorphism, Tyr/Ser, at the position of residue 703, caused by an A-C nucleotide substitution at position 2108 of the coding region. We examined the genotype frequencies for this polymorphism among Japanese using the PCR-SSP method. The genotypic frequencies were Gov^a/a, 23.5% ;Gov^a/b, 52.1% and Gov^b/b, 24.4%. Allele frequencies were 0.495 and 0.505 for Gov^a and Gov^b, respectively (n=217). Gov alloantibodies are the cause of neonatal alloimmune thrombocytopenic purpura (NAITP) and post-transfusion purpura, and are implicated in platelet transfusion refractoriness (PTR). On the basis of the Gov genotyping described here, Gov antigen panels can be prepared for the detection of anti-Gov antibodies in the sera of patients affected by NAITP and PTR.

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In order to decrease the contamination of blood components by bacteria, a diversion pouchintegrated blood collection system is being introduced to blood donation programs in some countries in Europe. The system is designed to collect the first 20-30mL of blood into a diversion pouch before blood collection, thereby eliminating the blood that may be contaminated by the highest number of bacteria residing on the skin. To verify the efficacy of this system on bacterial removal, blood aliquots drawn from the bacteria-coated juglar vein of dogs were serially cultured. It was observed that the number of cfu of bacteria decreased as the pre-donation sampling volume increased and no bacterial colony was detected in tubes after diversion of the first 27.0mL of blood. A blood collection kit for platelet apheresis was integrated with this satellite bag circuit and was tried on a volunteer for platelet collection. No serious problems were encountered except for the unusable volume of 20mL of blood collected in the pouch. The strategy of discarding the first 20-30mL of blood before collection may decrease the rate of bacterial contamination of blood components, especially of apheresis-derived platelet concentrates.

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The Committee for Blood Transfusion Therapy of Hyogo Prefectural Awaji Hospital undertook to check the rationale of emergency blood transfusions conducted in the hospital in December, 2000. If the transfusion therapy seemed inadequate, the Committee could send a warning message to the doctor who determined the therapy. The average volume of MAP transfused was 4.9±4.9 units. The hemoglobin value triggering the start of blood transfusion was 7.3±2.2g/dl, and the hemoglobin level reached was 8.8±2.0g/dl. It is difficult to change conventional practice in blood transfusion, and the problem of cost vs. safety remains controversial.

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