Comparison of different methods of anti-HLA antibodies detection in diagnosis of antibody-mediated renal allograft rejection
Aim: to analyze the relationship between circulating anti-HLA antibodies (class-I and class-II), renal pathology and C4d deposition in cases of late acute and chronic antibody-mediated renal allograft rejection according to the method of antibodies detection (ELISA and LUMINEX). Materials and methods. The study included 192 patients with indicative graft biopsies (with C4d-staining) and screening detection of anti-HLA antibodies (109 patients by ELISA, 58 patients by LUMINEX, 25 patients - both methods). Patients were divided into 3 groups based on pathology findings: 85 patients with chronic graft rejection, 39 patients with acute antibody-mediated rejection (AMR), 68 patients of control group had no signs of AMR. Results. Anti-HLA antibodies (predominantly class-II anti-HLA) were identified in 84.7% of patients with chronic graft rejection, in 84.6% of patients with acute AMR and 33.8% of control group (р < 0.001). Close correlation between the levels of anti-HLA antibodies detected by different methods was revealed for both classes of antibodies (r<sup>2</sup> class-I anti-HLA = 0.773, r2 class-II anti-HLA = 0.379, р < 0.01). LUMINEX proved to be more sensitive in anti-HLA antibodies detection in all groups. It was especially significant for the diagnosis of C4d-negative acute AMR whose frequencies were 22.2% and 4.8% in detection by LUMINEX and ELISA, respectively (р < 0.01). On the other hand, anti-HLA antibodies being detected by LUMINEX in 55% of patients of the control group more often required determination of donor specificity. Conclusion. Screening of anti-HLA antibodies (by ELISA and LUMINEX) along with specific renal pathology and C4d deposition is sufficient for the diagnosis of acute and chronic AMR in most cases. Being more sensitive LUMINEX method is preferable for the revealing of C4d-negative AMR, but it requires specific DSA detection in many cases.