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

Abstract

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.

Keywords: Anti-HLA antibodies; DSA; Kidney transplant; Single antigen assay; Xm-DSA assay.