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Background: Human leukocyte antigen (HLA)-C is expressed on nucleated cells and platelets in lower levels than HLA-A,B, and its antigens are in linkage disequilibrium with HLA-B antigens. Therefore, HLA-C antibody detection is difficult. The authors questioned whether HLA-C could serve as a target in clinical kidney transplantation using a newly developed assay., Methods: Flow cytometry was performed with sera from patients (n=34) awaiting a kidney retransplant using nine cell lines expressing a single HLA-C antigen (single-antigen lines [SAL])., Results: The SAL were validated with HLA-C-specific alloantisera and human monoclonal antibodies against HLA-A, -B, and -C. The results were in agreement with the specificities previously reported. Exceptions, because of new HLA-C specificities used here, could be explained by epitope sharing between the antigens. With respect to patient sera, 15 of the 34 patients tested (44%) showed serum reactivity toward one or more HLA-C SAL., Conclusions: In contrast to peripheral blood lymphocytes, SAL are excellent targets for detecting HLA-C-reactive alloantibodies by flow cytometry. This preliminary analysis revealed that HLA-C-reactive antibodies are frequently present in sera of retransplant patients, serving as possible targets in clinical transplantation.

Chronic allograft nephropathy (CAN) represents a frequent and irreversible cause of long-term renal graft loss. TGF-beta1 is a key profibrogenic cytokine associated with CAN pathogenesis. Because of clinical diagnostic inaccuracy, protocol biopsy has been suggested to be a beneficial method for early CAN detection. Protocol core biopsy was carried out in 67 consecutive cyclosporine-based immunosuppression-treated kidney transplant recipients with stable renal function 12 months after renal transplantation. Biopsy specimens were analyzed morphologically according to Banff-97' criteria and immunohistologically for TGF-beta1 staining. The data obtained were correlated with plasma TGF-beta1 levels and clinical data. CAN (grade I-III) was found in 51 patients (76 %). CAN grade I was found to be the most frequent one (44 %). A normal finding within the graft was made in only 12 patients (18 %). Clinically silent acute rejection Banff IA was present in 4 patients (6 %). In 8 patients (12 %) with CAN, borderline changes were present. We found a significant correlation between CAN grade and creatinine clearance, as measured by the Cockroft-Gault formula (p<0.01) as well as body mass index (p<0.01). There was a significant correlation between chronic vasculopathy (Banff cv) and creatinine clearance, and between the degree of TGF-beta1 staining and chronic vasculopathy (p<0.01). There were no relations between morphological findings and TGF-beta1 plasma levels, cyclosporine levels, plasma lipids, HLA-mismatches, panel reactive antibodies (PRA), proteinuria, and the donor's age. In conclusion, CAN is a frequent finding in protocol kidney graft biopsies 12 months after transplantation. TGF-beta1 tissue expression is linked with chronic vasculopathy.

The discrepancy between the increasing number of patients listed for kidney transplantation and limited cadaver donor sources has led the transplant community towards indication of elderly people as potential kidney donors. Based on clinical data, the kidney grafts explanted from aged donors have limited survival rates compared with younger ones. The donor age has been also implicated as the important alloantigen-independent risk factor for later onset of chronic allograft neprohopathy called chronic rejection. In this review we focused on some pathophysiological aspects of kidney aging and on the fate of transplanted kidney removed from elderly donors.