Naturally occurring interference in Luminex assays for HLA-specific antibodies: characteristics and resolution

Substances occurring naturally in the sera of patients can interfere with Luminex antibody assays, causing increased background and changes in antibody specificity. We present data on the effectiveness of hypotonic dialysis (HD) or dithiothreitol (DTT) treatment in eliminating this interference. HD significantly increased reaction strength of positive control beads and reduced reaction strength of negative control beads. HD also improved specificity identification, determination of donor-specific antibody (DSA) strength, and crossmatch predictability compared with values in untreated serum. DTT also increased the reaction strength of positive control beads, but in most cases, further increased reactivity of negative control beads. DTT improved crossmatch predictability but to a lesser extent than did HD and may differ with specificities defined in other assays. Because interference is frequently observed in sera from highly sensitized patients, it is important to recognize and eliminate interference in Luminex antibody assays for accurate and meaningful test interpretation.