Relevance of posttransplant HLA class I and class II antibodies on renal graft outcome

Post-transplant HLA class II antibodies and high soluble CD30 levels are independently associated with poor kidney graft survival

HLA-specific antibodies (HSA) and soluble CD30 (sCD30) were measured in 208 renal transplant recipients with functioning grafts at least 1 year after transplantation (median 8.2 years) to investigate the predictive value of HSA and sCD30 on subsequent graft outcome. HSA (class I and class II) were detected by both ELISA LAT-M and Luminex LabScreen assays. Data on graft outcome was collected with a median follow-up time of 3.5 years after antibody and sCD30 measurement. Recipients with post-transplant HLA class II antibodies had particularly poor graft outcome with a hazard ratio (HR) of 7.8 (p < 0.0001) when detected by ELISA, and a HR of 6.0 (p < 0.0001) when detected by Luminex. A high post-transplant sCD30 level >or=100 U/mL was associated with increased risk of subsequent graft failure (HR 2.7, p = 0.03). sCD30 and HSA had an independent and additive association with graft outcome. Recipients with HLA class II antibody and high sCD30 had the highest risk of subsequent graft failure (HR 43.4, p < 0.0001 and HR 18.1, p = 0.0008 for ELISA and Luminex, respectively). These data show that detection of HSA and serum sCD30 measured at least 1-year post-transplant provides valuable and predictive information regarding subsequent graft outcome.

The dynamics of antidonor antibody formation early after clinical kidney transplantation measured by flow cytometry and microcytotoxicity test

To study the dynamics of antidonor sensitization 92 patients were monitored for antibodies against donor T and B spleen lymphocytes before transplantation, within the first month after transplantation and 3 months after transplantation. Patients were monitored for donorreactive antibodies (DRA) of immunoglobulin G (IgG), IgA, and IgM isotype using flow cytometry (FC) and the standard microcytotoxicity test (CYT). Graft function was followed for at least 2 yrs, 51% of patients for 3 yrs after transplantation. Within the first month after transplantation the percentage of patients with antidonor sensitization detected by FC rose dramatically, so that the overall sensitization rate increased from 28 (30.4%) of 92 patients prior to transplantation to 63 (68.5%) of 92 patients after transplantation. Whereas preoperatively only one isotype (IgM for T lymphocytes, IgG for B lymphocytes) and only one target cell type (either T or B lymphocytes) dominated, the postoperative patterns of positive FC results were more variable regarding target and isotype, whereby FC-DRA of the IgA class substantially contributed. Appearance of donor-directed antibodies early after kidney transplantation is a frequent event. In our cases, sensitization with FC-DRA per se seemed not to be detrimental to the graft outcome (p > 0.05) but CYT-DRA did resulting in a significant poor graft outcome 3 months after transplantation (p < 0.001).