Date: Saturday, May 30, 2020
Session Time: 3:15pm-4:00pm
Presentation Time: 3:30pm-4:00pm
*Purpose: Immunoglobulin M (IgM) deposition in peritubular capillaries (PTCs) is rarely identified in renal allograft biopsies of ABO-compatible kidney transplantation. In ABO-incompatible kidney transplantation (ABOI-KTx) IgM deposition in PTCs is sometimes identified probably due to anti-blood group IgM antibodies, however the clinical relevance of IgM deposition in PTCs is not clearly understood. The objective of the current study was to investigate the clinical relevance of IgM deposition in PTCs in the early period after ABOI-KTx.
*Methods: Methods: This retrospective study included 140 recipients who received ABOI-KTx at Tokyo Women’s Medical University between 2005 and 2013 and underwent at least one renal allograft biopsy within 3 months after transplantation. The patients were divided into two groups based on IgM deposition in PTCs on graft biopsies obtained 3 months post-transplant, and IgM-positive group (n = 40) and an IgM-negative group (n = 140). Of the recipients who underwent more than one biopsy within 3 months post-transplant, those who had at least one IgM-positive biopsy were included in the IgM-positive group. IgM deposition was evaluated via immunofluorescence staining on cryosections, and diffuse bright staining along PTCs was regarded as positive. All IgM-positive renal allograft biopsies exhibited C4d deposition in PTCs.
*Results: The incidence of acute antibody-mediated rejection within 3 months after transplantation did not differ significantly in the two groups (IgM-positive n = 10; 25% vs. IgM-negative n = 17; 17%, p = 0.278). There was no significant difference between the two groups in death-censored graft survival ((IgM-positive vs. IgM-negative: 5 year 95% vs. 95%, log rank test 0.830). Mean serum creatine did not differ significantly in the two groups at any time‑point during the follow-up period (IgM-positive vs. IgM-negative, mg/dL: 1 year 1.34 vs. 1.28; 3 years 1.26 vs. 1.27; 5 years 1.28 vs. 1.28). The incidence of chronic antibody-mediated rejection did not differ significantly in the two groups (IgM-positive n = 5; 12%, IgM‑negative n = 11; 11%, p = 0.801). Patient characteristics were relatively similar, but median pre-transplant baseline anti-blood group IgM antibody titer was significantly higher in the IgM-positive group (64 vs. 32, p = 0.001).
*Conclusions: IgM deposition in PTCs was observed in approximately 30% of patients with ABOI-KTx within 3 months post-transplant. Anti-blood group IgM antibodies may be attributed to IgM deposition in PTCs, but the clinical relevance of IgM deposition in PTCs remains unclear in cases of ABOI-KTx.
To cite this abstract in AMA style:Toki D, Okumi M, Unagami K, Kakuta Y, Ishida H, Yamashita K, Tachibana H, Hayashida A, Horiuchi T, Ishiyama Y, Honda K, Kondo T, Tanabe K. Clinical Relevance of Immunoglobulin M Deposition in Peritubular Capillaries in ABO-Incompatible Kidney Transplantation [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/clinical-relevance-of-immunoglobulin-m-deposition-in-peritubular-capillaries-in-abo-incompatible-kidney-transplantation/. Accessed February 27, 2021.
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