Evaluation of anti-human leukocyte antigen allo-immunization in pediatric cadaveric kidney transplantation.

Forty-eight pediatric cadaveric renal transplantations, performed between May 1986 and February 1997, were retrospectively screened, pre- and post-transplant, for antibodies to human leukocyte antigen (anti-HLA) using complement-dependent cytotoxicity (CDC) assay and enzyme immunoassay (EIA). The correlation between anti-HLA immunization and graft outcome was investigated. The combined analysis of CDC and EIA enabled the differentiation between complement-fixing and non-complement-fixing, anti-HLA class I and anti-HLA class II antibodies. The median post-transplant follow-up for all patients with a functioning graft was 86 months (range 10-138 months). In the whole population, 16 grafts were lost: six following a non-immunologic complication; and 10 as a result of rejection. Of these 10 grafts lost, eight were in patients with pre- and/or post-transplant donor antigen specific (DAS) anti-HLA class I or class I + II antibodies; and two were in patients with DAS anti-HLA class II antibodies only. Three of these grafts were lost in patients with weak pre-existing DAS anti-HLA class I antibodies. Immunological graft loss appeared at a median post-transplant time of 38 months (range 2-68 months). All patients without DAS anti-HLA antibodies had a good graft outcome. The presence of pre- and post-transplant DAS anti-HLA antibodies, especially if directed against HLA class I, were associated with a poor graft outcome. A systematic search for, and identification of, anti-HLA antibodies should therefore be part of a pretransplant evaluation to allow the identification of 'unacceptable' donor HLA antigens, following which the impact of the HLA-cross-match on graft outcome will improve. Screening for DAS anti-HLA antibodies post-transplant could be helpful for detecting patients with an increased risk for graft loss following rejection episodes.

An EIA method on single donor solubilized HLA antigens for the identification of anti-HLA antibodies.

An enzyme immunoassay (EIA) method based on solubilized human leucocyte antigens (HLA) derived from single donor platelets is described. The EIA results on these solubilized single donor HLA antigens (SDszHLA) correlated well with the complement dependent cytotoxicity (CDC) results on the lymphocytes of the same donors and also with the panel reactivity (PRA) in CDC. A concordancy rate of 78% was found for individual HLA specificities. The EIA+/CDC- ('false positive') discrepancies were more pronounced than EIA-/CDC+ ('false negative') discrepancies and varied for the different donors. To confirm discrepancies, our method was compared with a commercial PRA-STAT EIA method (based on secreted soluble HLA antigens). The same discrepancies between CDC and PRA-STAT EIA were found and are probably due to the higher and different sensitivity (e.g. non complement fixing antibodies) of EIA methods. A SDszHLA EIA method allows the identification of HLA specificities of HLA-antisera. The possibility of using individual and selected donors for the production of SDszHLA allows the directed search for well defined HLA specificities in order to confirm anti-HLA specificities found in other anti-HLA screening methods. An individualized HLA panel can be established with the support of blood banks that have HLA typed blood and platelet donors.

A single center evaluation of the Collaborative Transplant Study (CTS) DNA project.

Historical HLA class II serological typing results of transplantations performed in "The Leuven Collaborative Group for Transplantation" were subjected to retrospective Restriction Fragment Length Polymorfism (RFLP) DNA control typing by the Collaborative Transplant Study (CTS) DNA project using Polymerase Chain Reaction (PCR)-based DNA methods. We re-evaluated the serology/ RFLP-discrepant CTS DNA data for our local patients transplanted during a historical period (January 1988 until May 1992) before any class II DNA typing was performed in our tissue typing laboratory. These retyping results confirm both the CTS data for patient typing and the Eurotransplant data for donor typing. A confirmed high discrepancy rate of 19.0% (after exclusion of 2.2% transcription errors) was found in the patient population. A low discrepancy rate of 6.8% (after exclusion of 2.2% transcription errors) for the donor population is concordant with the Eurotransplant donor data. Only 4 of the 588 individuals were found to be incorrectly typed by the RFLP method; all involving the specificities DRB1*1102. This indicates that RFLP typing, as performed by the CTS DNA project, can be considered a valid, retrospective DNA typing system for the accurate interpretation of class II matching in organ transplantation. A second conclusion to be drawn from this study is the need for prospective DNA typing for kidney transplant recipients, as the discrepancy rate in this cohort is high. Our results suggest that with good quality serological HLA-DR typing, prospective donor DNA typing is not urgently needed.