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Objectives: Many researchers have demonstrated that the seropositivity rate after SARS-CoV-2 coronavirus vaccination is lower in patients receiving oral immunosuppressants. In this article, we report on a comparative study on the seropositivity rate after 2 doses of coronavirus vaccine before or after kidney transplant., Materials and Methods: We studied 111 recipients vaccinated after transplant, 19 patients vaccinated before transplant, and 10 healthy patients. We retrospectively measured antibody titers using preserved serum samples. The antibody testing was performed 1 month and 3 months after vaccination. The measurement was via LABScreen COVID Plus, which enables simultaneous determination of 5 coronavirus protein antigens., Results: Seropositivity to coronavirus antibodies was observed in all 19 patients vaccinated before transplant (100%) and in all the 10 healthy patients (100%). Forty- six of the 111 recipients (42%) vaccinated after transplant developed seropositivity. Analyzed at each time point after vaccination, the mean fluorescence intensity of antibodies was unchanged between 1 month and 3 months after vaccination in transplant recipients who were vaccinated after transplant and developed seropositivity. On the other hand, the antibody mean fluorescence intensity in patients vaccinated before transplant was markedly lower at 3 months (posttransplant)., Conclusions: All patients with renal failure who were vaccinated before transplant showed a high seropositivity rate, similar to that in healthy patients. The seropositivity rate for each of the viral fragment antibodies in patients vaccinated before transplant was maintained, as seen in healthy patients. However, in patients vaccinated before transplant who tested positive for antibody production at 1 month after vaccination,the antibody mean fluorescence intensity at 3 months after vaccination (posttransplant) was remarkedly lower than the mean fluorescence intensity at 1 month, which was probably caused by the types of immunosuppressive regimens used atthe time of transplant.

Objectives: Although the effectiveness of vaccines in protecting the host from infection has been proven, few surveys have been conducted on changes in antibody levels after vaccination of kidney transplant recipients in Japan., Materials and Methods: We analyzed serological responses in kidney transplant recipients after BNT162B2 COVID-19 mRNA vaccine with the use of a reagent capable of simultaneously specifying the antibody response to 5 proteins: a full-spike protein (extracellular domain), 3 individual domains of the spike protein (S1, S2, and receptor-binding domain), and nucleocapsid. The analysis involved 111 patients who had follow-up over 1 month after having received the second of 2 coronavirus vaccines after kidney transplant., Results: Antibodies were detected in 46 of 111 patients (41%). The antibody-positive rate in the kidney transplant group tended to be lower than that in the healthy control group, which showed an antibody- positive rate of 100%. When the antibody-positive rate was analyzed by the type of immunosuppressor used, the rate was 36% (37/100) for patients who used tacrolimus at the time of vaccination and 90% (9/10) for patients who used cyclosporine. Patients administered CD20 antibody (rituximab) before and/or after transplant showed a lower production of antibodies, which was supported by a smaller number of CD19- and CD20-positive cells in the peripheral blood as well as a shorter period between rituximab administration and vaccination. The percentage of responding viral fragments varied greatly among individual patients and showed no uniformity in the kidney transplant group, whereas the mean fluorescence intensity of individual fragments showed a certain tendency in the control group., Conclusions: The appropriate timing of vaccination should be considered in transplant recipients who use tacrolimus-mycophenolate mofetil combination and rituximab as these drugs are deeply related to a lower antibody response to SARS-CoV-2 BNT162b2 vaccination.

Objectives: Antibody-mediated rejection in patients with positive crossmatches can be severe and result in sudden onset of oliguria, leading to graft loss. In an attempt to prevent posttransplant oliguria, we adopted a preoperative desensitization protocol involving the use of high-dose intravenous immunoglobulin/plasmapheresis and the anti-CD20 antibody, rituximab, in 41 transplant recipients with positive crossmatch test results., Materials and Methods: We retrospectively examined the clinical courses of the 41 kidney transplant recipients, paying special attention to renal graft function, urine volume, and changes in the titers of donor-specific antibodies., Results: Four grafts were lost during an average of 4.5-year follow-up. Average graft function was excellent, with a serum creatinine level of 1.3 ± 0.4 mg/dL. Sufficient urine output, with no oliguria or anuria, was achieved postoperatively in 40 of the 41 patients. However, among the 34 patients who underwent graft biopsies, the biopsies revealed acute antibody-mediated rejection in 21 patients (62%), and chronic antibodymediated rejection in 10 patients (30%)., Conclusions: The high-dose intravenous immunoglobulin treatment included in our desensitization protocol was shown to be safe and effective for achieving successful transplant outcomes and allowed the avoidance of more aggressive B-cell-targeted treatments, such as C5 inhibitors and/or proteosome inhibitors, for preventing posttransplant oliguria and anuria.