THE TRANSPLANT OF IMMUNIZED PATIENTS: FOUR YEARS OF EXPERIENCE IN A SINGLE CENTRE USING AN ELISA METHOD DETECTING ANTI HLA SPECIFICITY

Abstract

575 Since immunized patients are still representing one of the unsolved problems in kidney transplantation, aim of this study is to ascertain if an accurate immunological screening before transplantation (i.e. the detection of HLA Class I antibody specificities) and a high HLA match, are able to make the graft possible and successful. 284 patients submitted to cadaver donor kidney transplantation from 1994 to 1997 were divided in four groups on the basis of the peak panel reactive antibodies (PRA) value: group A included 34 immunized patients with at least 1 PRA > 50% (PRA peak 62.5±15.4%, average PRA 15.7±6.0%), group B included 9 hyperimmunized patients with more than 3 PRA over 50% (PRA peak 79.4±12.6%, average PRA 31.6±12.4%) and group C 9 re-transplanted patients (PRA peak 47.7±38.7%, average PRA 19.5±21.3%). The fourth group - 232 control patients - (PRA peak 19.1±12.8%, average PRA 6.6±5.1%), was well matched considering sex, age, blood group, donor age difference, cold ischemia time and functional recovery. In addition to the standard methods, patients were studied before transplantation with HLA Class I antibody specificity determination (Elisa method PRASTAT© SANGSTAT), with the knowledge of typing of previous graft donor, of husband in multipregnancy women and of potential donors against which candidates gave positive cross-match. At the graft, once excluded the presence of the HLA class I antigens previously detected, an high HLA (Class I and II) compatibility was looked for (HLA Molecular typing), and donor-recipient cross-match test was performed both with Light Microscopy and CDC-Flow Cytometry. Once transplanted, group A, B and C patients were submitted to steroids, cyclosporine and ATG/ALG since first days and when ATG/ALG lasted, azatioprine was introduced. Comparison of the four groups showed significant data: 1) PRASTAT© determinations were statistically significant to discriminate between the groups thus confirming its prognostic role: 13.6% of patients showed anti-HLA specificity in the group-A, 66.6% in the group B, 77.7% in the group C while the detected specificity was 4.7% in controls (p<0.001). PRASTAT© value was 2.2±6.1% in group A, 12.8±18.2% in group B*, 20.3±18.7% in group C* and 1.76±3.9% in controls (*P<0.001). 2) HLA mis-matches were lower: HLA-Class I 2.42±1.0 (A, p<0.05), 1.89±0.93 (B, p<0.01), 2.06±0.88 (C, p<0.02) vs. 2.75±0.85 (n.s.), HLA-DR 0.68±0.54 (A, p<0.05), 0.44±0.53 (B, p<0.02), 0.47±0.5 (C, p<0.05) vs. 0.94±0.61 (controls). 3) Actuarial graft survival after 12 months was satisfying for all patients: 89% (A), 89% (B), 78% (C) vs. 92% (controls). Renal function at the end of the first year was similar: serum creatine 1.56±0.6 mg/dl (A), 1.53±0.5 (B), 1.43±0.31 (C) vs. 1.49±0.4 (controls) and the number of rejection episodes in the first 3 months was not different: 0.47±0.5 (A), 0.50±0.5 (B), 0.63±0.5 (C) vs. 0.54±0.64 (controls).