HLA and lung transplantation

International audienc

Anti-HLA sensitization after kidney allograft nephrectomy: changes one year post-surgery and beneficial effect of intravenous immunoglobulin

International audienceThe analysis of anti-HLA sensitization at the time of and following allograft nephrectomy may help clinicians to define better both the indications for nephrectomy and preventive therapeutic strategies. We carried out a retrospective analysis of anti-HLA antibodies in 63 clinically indicated nephrectomies (baseline and three and 12 months after) according to the time elapsed since transplantation (six months) and clinical background. An intervention study included 10 patients without donor-specific antibodies (DSA) at the time of nephrectomy treated with high-dose intravenous immunoglobulin (IVIG) (1.5 g/kg). Early nephrectomies were performed in 15 patients (24%). Among the late nephrectomies, 14 patients (22%) were asymptomatic and 34 (54%) had graft intolerance syndrome (GIS). At baseline, anti-HLA sensitization was significantly lower in the early and late asymptomatic groups than in the GIS group, but increased considerably within the three months following surgery. In the group of 10 patients treated with IVIG, only the number of class I non-DSA increased in the three months after surgery, whereas in the control group (N = 13), all anti-HLA variables increased significantly. All patients undergoing a clinically indicated allograft nephrectomy become highly sensitized within the 12 months after surgery. In patients without DSA before nephrectomy, high doses of IVIG may prevent anti-HLA sensitization

Complement-binding anti-HLA antibodies are independent predictors of response to treatment in kidney recipients with antibody-mediated rejection

A major hurdle to improving clinical care in the field of kidney transplantation is the lack of biomarkers of the response to antibody-mediated rejection (ABMR) treatment. To discover these we investigated the value of complement-binding donor-specific anti-HLA antibodies (DSAs) for evaluating the response to treatment. The study encompassed a prospective cohort of 139 kidney recipients with ABMR receiving the standard of care treatment, including plasma exchange, intravenous immunoglobulin and rituximab. Patients were systematically assessed at the time of diagnosis and three months after treatment initiation for clinical and allograft histological characteristics and anti-HLA DSAs, including their C1q-binding ability. After adjusting for clinical and histological parameters, post-treatment C1q-binding anti-HLA DSA was an independent and significant determinant of allograft loss (adjusted hazard ratio 2.57 (95% confidence interval 1.29-5.12). In 101 patients without post-treatment C1q-binding anti-HLA DSA there was a significantly improved glomerular filtration rate with significantly reduced glomerulitis, peritubular capillaritis, interstitial inflammation, tubulitis, C4d deposition, and endarteritis compared with 38 patients with posttreatment C1q-binding anti-HLA DSA. A conditional inference tree model identified five prognostic groups at the time of post-treatment evaluation based on glomerular filtration rate, presence of cg lesion and C1q-binding anti-HLA DSA (cross-validated accuracy: 0.77). Thus, circulating complement-binding anti-HLA DSAs are strong and independent predictors of allograft outcome after standard of care treatment in kidney recipients with ABMR

Donor‐specific HLA antibody‐mediated complement activation is a significant indicator of antibody‐mediated rejection and poor long‐term graft outcome during lung transplantation: a single center cohort study

Complement-mediated allograft injury, elicited by donor-specific HLA antibodies (DSA), is a defining pathophysiological characteristic of allograft damage. We aimed to study DSA-induced complement activation as a diagnostic marker of antibody-mediated rejection (AMR) and a risk stratification tool for graft loss in the context of lung transplantation (LT). We identified 38 DSA-positive patients whose serum samples were submitted for C3d deposition testing via the C3d assay. Among these 38 patients, 15 had AMR (DSAPos AMRPos ). Results were reported for each patient as the C3d ratio for each DSA, the immunodominant DSA, and the C3d ratio for all DSA present in a sample (C3d ratioSUM ). DSAPos AMRPos patients had higher C3d ratioSUM values (58.66 (-1.32 to 118.6) vs. 1.52 (0.30 to 2.74), P = 0.0016) and increased immunodominant C3d ratios (41.87 (1.72 to 82.02) vs. 0.69 (0.21 to 1.19), P = 0.001) when compared with DSAPos AMRNeg patients. Specificity and calculated positive predictive value of the immunodominant C3d ratio and BCMsum tests for AMR diagnosis were both 100% (CI = 17.4-100) in this cohort. Worst graft survival was associated with both immunodominant C3d ratio ≥4 or C3d ratioSUM ≥10 or BCMsum >7000, suggesting that the antibody composition and/or strength are the principal determinants of an HLA DSA's capacity to activate complement

Minimizing the risk of allo-sensitization to optimize the benefit of allogeneic cardiac-derived stem/progenitor cells

International audienc

Maintaining calcineurin inhibition after the diagnosis of post-transplant lymphoproliferative disorder improves renal graft survival

International audiencePost-transplant lymphoproliferative disorder (PTLD) is an uncontrolled proliferation of transformed lymphocytes fostered by immunosuppression. In addition to chemotherapy, treatment of PTLD includes a reduction of maintenance immunosuppression. Patients with PTLD have an increased risk of graft loss, suggesting that reduced immunosuppression strategy needs to be optimized with regard to graft outcome. Here we retrospectively reviewed 101 cases involving PTLD to identify the risks associated with graft loss. During a median follow-up of 70 months, 39 patients died and 21 lost their graft. Multivariate analysis found that an eGFR under 30 ml/min per 1.73 m(2) at PTLD diagnosis, a biopsy-proven acute rejection episode following reduction of immunosuppression, and the absence of calcineurin inhibition in maintenance immunosuppression are independent risk factors for allograft loss. Neither the type of PTLD nor the chemotherapy regimen was predictive of allograft failure. Histological analysis of graft biopsies showed that maintaining calcineurin inhibition after the diagnosis of PTLD reduced the risk of developing de novo anti-HLA antibodies and humoral rejection. Remarkably, calcineurin inhibitor maintenance was neither associated with higher mortality nor with worse progression-free survival. Thus, maintaining calcineurin inhibition at a reduced dose after the diagnosis of PTLD seems safe and may improve renal graft outcome, possibly through better control of the recipient's humoral immune response

Antibody-mediated rejection in pediatric small bowel transplantation: Capillaritis is a major determinant of C4d positivity in intestinal transplant biopsies

The diagnostic criteria for antibody-mediated rejection (ABMR) after small bowel transplantation (SBT) are not clearly defined, although the presence of donor-specific antibodies (DSAs) has been reported to be deleterious for graft survival. We aimed to determine the incidence and prognostic value of DSAs and C4d in pediatric SBT and to identify the histopathologic features associated with C4d positivity. We studied all intestinal biopsies (IBx) obtained in the first year posttransplantation (N = 345) in a prospective cohort of 23 children. DSAs and their capacity to fix C1q were identified by using Luminex technology. Eighteen patients (78%) had DSAs, and 9 had the capacity to fix C1q. Seventy-eight IBx (22.6%) were C4d positive. The independent determinants of C4d positivity were capillaritis grades 2 and 3 (odds ratio [OR] 4.02, P = .047 and OR 5.17, P = .003, respectively), mucosal erosion/ulceration (OR 2.8, P = .019), lamina propria inflammation grades 1 and 2/3 (OR 1.95, P = .043 and OR 3.1, P = .016, respectively), and chorion edema (OR 2.16, P = .028). Complement-fixing DSAs and repeated C4d-positive IBx were associated with poor outcome (P = .021 and P = .001, respectively). Our results support that capillaritis should be considered as a feature of ABMR in SBT and identify C1q-fixing DSAs and repeated C4d positivity as potential markers of poor outcome