Body: Third-party vessel allografts (3rdVA) are used in kidney transplantation when vascular reconstruction is required but suitable vessels from the kidney allograft donor are unavailable. Here, we report two cases to evaluate the influence of 3rdVA on kidney transplant outcomes. Case 1: A 68-year-old male underwent kidney/3rdVA transplantation with a negative flow cytometry crossmatch (FCXM) and no DSA (PRA = 0%). The kidney allograft was removed on post-operative day (POD) 257 due to carcinoma without evidence of antibody-mediated rejection (AMR) or acute cellular rejection (ACR). However, a significant increase in PRA (98%) was observed. The patient underwent a second kidney/3rdVA transplant 2.5 years after allograft nephrectomy, with negative FCXM and no DSA to the second kidney allograft (PRA = 92%). However, DR1 (which was also a mismatch from the first kidney allograft) and DR4 DSAs to the second 3rdVA were detected. With a follow-up of 210 days, there have been consistently no detectable DSA to the second kidney, no evidence of AMR, and no concern for damage to the second 3rdVA, despite persistently strong DR1 and DR4 DSAs to the 3rdVA (Fig. 1). Case 2: A 52-year-old male underwent kidney/3rdVA transplantation with a negative FCXM and no DSA (PRA = 0%). On POD 453, multiple de-novo DSAs, particularly strong class I, to the 3rdVA, were detected, along with a significantly elevated PRA (99%). A biopsy revealed ACR, but no AMR (no DSA to the kidney allograft ). Timely treatment with methylprednisolone followed by 6 mg/kg anti-thymocyte globulin for ACR and 2 g/kg intravenous immunoglobulin for DSA prevented further episodes of ACR and led to a reduction in DSAs by POD 541. Although some DSAs remained persistently strong after treatment (Fig. 2), there was no evidence of damage to the 3rdVA.
Conclusion: Kidney transplantation involving a 3rdVA was associated with increased PRAs in both cases and with ACR in Case 2, likely due to the enhanced immunogenicity induced by the 3rdVA. Notably, both cases never developed DSA or AMR to the kidney allografts. Despite the presence of multiple, persistent, and strong DSAs to the 3rdVAs in both cases, no functional impairment of the 3rdVA was observed, suggesting a delayed or absent impact of DSA on 3rdVA function. A cohort study is warranted to confirm these findings.
