Antibody monitoring system to support the single-antigen Luminex assay in donor-specific antibody detection

Comparative analysis of two methods to detect donor-specific anti-HLA antibodies after kidney transplant

Preformed anti-human leukocyte antigen (HLA) antibodies may be present in the blood of kidney transplant candidates. The production of these antibodies may occur in the post-transplant period, with the possible development of donor-specific antibodies (DSA). Luminex-based tests, such as the single antigen (SA) assay and the Luminex crossmatch (Xm-DSA) assay are the most commonly used tools to detect anti-HLA antibodies, due to their high sensitivity and specificity. This cross-sectional study aimed to compare the findings of two methods for the detection of DSAs after kidney transplant: SA and Xm-DSA. A total of 122 patients who underwent deceased donor kidney transplant at Hospital de Clínicas de Porto Alegre were included. The SA assay detected anti-class I HLA DSAs in 17 patients (13.9%) and anti-class II HLA DSAs in 22 patients (19.6%), whereas the Xm-DSA detected DSAs in 18 patients (14.8%) both against class I and class II antigens. There was agreement between the two methods for class I (kappa = 0.66, p = 0.001) and class II (kappa = 0.54, p = 0.025) antigens. The incidence of DSAs as obtained by the SA assay was 15.57%, and the most prevalent DSAs were those against HLA-DR antigens. Patient survival at 3 years was 92%. The two techniques assessed in this study provide important information on the presence of DSAs and may help in the post-transplant patient monitoring and in immunosuppressive strategy.

Clinical significance of the presence of anti-human leukocyte antigen-donor specific antibody in kidney transplant recipients with allograft dysfunction

BACKGROUND/AIMS

This study investigated the clinical significance of detecting anti-human leukocyte antigen-donor specific antibody (HLA-DSA) in kidney transplant recipients (KTRs) requiring indication biopsy owing to allograft dysfunction.

METHODS

We analyzed the presence of HLA-DSA in 210 KTRs who took indication biopsy. We divided these cases into two groups, HLA-DSA (+) (n = 52) and HLA-DSA (-) (n = 158) group, and compared the clinical characteristics, pathological findings, and clinical outcomes of the two groups.

RESULTS

The rates of retransplant, pretransplant sensitization, and HLA-mismatch were significantly higher in HLA-DSA (+) group than in HLA-DSA (-) group (p < 0.05 for each comparison). In histologic finding, all types of rejections were more frequent in the former group. Besides, scores of both the T-cell injury markers such as tubulitis, interstitial inf lammation, and vasculitis and antibody-mediated injury markers such as peritubular C4d deposition and microvascular inflammation (glomerulitis plus peritubular capillaritis) were higher in HLA-DSA (+) group (p < 0.05 for each). Notably, allograft outcomes were worse in HLA-DSA (+) group. Further, multivariate analysis showed that presence of HLA-DSA, advanced interstitial fibrosis/tubular atrophy (interstitial fibrosis plus tubular atrophy ≥ 2), and allograft rejection in biopsy were independent risk factors for allograft failure.

CONCLUSIONS

The results of this study showed that presence of HLA-DSA in a case of allograft dysfunction adversely influences allograft outcome, and its detection, irrespective of the result of the allograft biopsy, necessitates intensive monitoring and treatment.