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In Japan, the complement-dependent cytotoxicity (CDC-crossmatch) test and the anti-donor antibody flow cytometric assay (FCXM) are used to evaluate presensitization among transplantation candidates. We introduced the flow cytometric panel reactive antibody method (FlowPRA) at our institution, and in this paper, we compared the results of FCXM and FlowPRA. Sera of a total of 238 patients receiving the first graft were analyzed by FlowPRA retrospectively. Specimens from 125 of these patients were also analyzed by FCXM, and the results obtained using the two methods were compared. In addition, postoperative pathological findings by graft biopsy were examined in patients with PRA class 1(+) or PRA class 2(+). (i) Class 1 antibodies were detected in 36 of the 238 patients (15%), class 2 antibodies in six patients (3%), and both class 1 and class 2 antibodies in five patients (2%). (ii) Totally 125 patients analyzed by both FCXM and FlowPRA, 28 patients (22%) who tested negative by FCXM were, however, found to be positive by FlowPRA, and 16 of these 28 patients (57%) had shown evidence of humoral rejection suspected of antibody-mediated in the early postoperative stage. A large proportion of patients who tested negative by FCXM but positive by FlowPRA experienced rejection. Thus, for detecting 'high responders' in patients receiving the first graft, use of FlowPRA to detect antibodies may be superior to that of FCXM.

Hemolysis may occur after organ transplantation. In most cases, hemolysis is drug-related, such as to cyclosporin, etc. However, it is important to consider graft-versus-host antibody formation as one of the causes of hemolysis. We evaluated the effect of local graft irradiation as a method of preventing hemolysis arising from ABO antibody formation after ABO-mismatched renal transplantations. The participants in this study were 44 patients who had undergone ABO-mismatched renal transplantation. Of these patients, 23 were subjected to postoperative local irradiation, and 21 were not. We examined the characteristics of anti-blood-type antibodies, and we also compared the frequency of the development of antibody formation and hemolysis development between the groups. The development rates of anti-ABO-antibody formation and hemolysis were significantly higher in the patients without local irradiation (15/21, 71%; 6/21, 29%) than in those with local irradiation (1/23, 4%; 0/23, 0%). The elevated antibodies mainly belonged to the IgG class, not the IgM class. The hemolysis- and antibody formation observed in the patients originally without postoperative local irradiation was dramatically improved by graft irradiation. Local graft irradiation after ABO-mismatched renal transplantations may be needed to prevent the formation of anti-ABO antibodies and to impede the development of hemolysis.