Donor-specific antibody detection: comparison of single antigen assay and Luminex crossmatches

Luminex bead‐based assays are routinely used in the study of anti‐human leukocyte antigen (HLA) donor‐specific antibodies (DSA). Single antigen (SA) assays use beads coated with recombinant antigens whereas Luminex crossmatch (Xm‐DSA) tests consist of beads coated with isolated donor‐specific HLA molecules. The aim of this study was to compare these techniques used to detect DSA. A total of 24 sera recognizing different HLA class I (seven anti‐HLA‐A and seven anti‐HLA‐B) as well as class II (seven anti‐HLA‐DR and three anti‐HLA DQ) specificities by complement dependent cytotoxicity were included in the study. These sera were used undiluted and in serial dilutions to perform both class I and II SA and Xm‐DSA assays. In the case of Xm‐DSA the same serum was checked with different lysates. A total of 42 lysates were used to perform a total of 61 crossmatches: 42 to detect anti‐class I and 19 to detect anti‐class II antibodies. The maximum positive dilution was higher for SA in 76% of the class I and in 90% of the class II crossmatches. Those cases with a higher sensitivity of the Xm‐DSA could not be explained by a larger number of antigen targets.