HLA class I peptide polymorphisms contribute to class II DQß0603:DQα0103 antibody specificity.

Antibodies reactive to human leukocyte antigens (HLA) represent a barrier for patients awaiting transplantation. Based on reactivity patterns in single-antigen bead (SAB) assays, various epitope matching algorithms have been proposed to improve transplant outcomes. However, some antibody reactivities cannot be explained by amino acid motifs, leading to uncertainty about their clinical relevance. Antibodies against the HLA class II molecule, DQß0603:DQα0103, present in some candidates, represent one such example. Here, we show that peptides derived from amino acids 119-148 of the HLA class I heavy chain are bound to DQß0603:DQα0103 proteins and contribute to antibody reactivity through an HLA-DM-dependent process. Moreover, antibody reactivity is impacted by the specific amino acid sequence presented. In summary, we demonstrate that polymorphic HLA class I peptides, bound to HLA class II proteins, can directly or indirectly be part of the antibody binding epitope. Our findings have potential important implications for the field of transplant immunology and for our understanding of adaptive immunity.

Optimal oncologic management and mTOR inhibitor introduction are safe and improve survival in kidney and liver allograft recipients with de novo carcinoma.

Prognosis and oncologic treatment feasibility in solid organ transplant patients with de novo cancer remain poorly described. We investigated the impact of immunosuppressive therapy modifications after de novo cancer diagnosis on oncologic treatment feasibility, toxicities, and prognosis. Patients with de novo cancer (excluding nonmelanoma skin cancers) were selected from a monocentric cohort of 4,637 kidney and liver allograft recipients. We assessed oncologic treatment optimality according to guidelines and analyzed immunosuppressive drug modifications and oncologic treatment impacts on treatment feasibility, toxicities, and graft/patient survivals. A total of 180 patients with 205 cancers were included: mean age 60 years, median delay from transplantation to first de novo cancer 5 years. In 46% of cases, immunosuppressive therapy was modified after cancer diagnosis: 24% dose reduction and 22% mTOR inhibitor introduction. Optimal oncologic treatment was performed in 80% and 38% of patients with localized and advanced cancer respectively. Transplantation and immunosuppression hindered optimal oncologic treatment in 11% instances. Immunosuppressive therapy modifications did not affect oncologic treatment tolerance nor graft survival. In multivariate analysis, optimal oncologic treatment and mTOR inhibitor introduction improved survival of patients with de novo carcinoma. Optimal oncologic treatment is feasible in kidney and liver allograft recipients without safety concerns. Optimal oncologic treatment and mTOR inhibitor introduction seem to markedly improve survival of patients with de novo carcinoma.

Outcome of second kidney transplantation in patients with previous post-transplantation Kaposi's sarcoma: A French retrospective study.

This retrospective study concerned 8 patients with post-transplantation Kaposi's sarcoma (pt-KS) after a first kidney transplant who later had a second kidney transplantation. Pt-KS was widespread, with lymph node or visceral involvement in 7 cases. Complete remission was observed in 6 cases and partial remission in 2. After the second kidney transplantation, only 2 cases showed recurrence of skin KS, one with previous complete remission of KS and one with partial remission. The mean delay between stability or complete remission of KS and retransplantation was 2.0 and 7.3 years in patients with and without relapse, respectively. Both recurrent cases showed complete KS remission after tapering immunosuppression therapy and/or switching a calcineurin inhibitor to a mammalian target of rapamycin inhibitor. We compared these 8 cases to 24 controls who had undergone 2 kidney transplantations but did not have KS, matching on sex, age and phototype. Cases and controls did not differ in graft function or survival. A second kidney transplantation may be possible after pt-KS and has acceptable risk, especially after a long complete remission of pt-KS.