Methodologies for anti-HLA antibody screening in patients awaiting kidney transplant: a comparative study

The relevance of anti-HLA antibodies in patients awaiting kidney transplants is well recognized. During the past 40 years, kidney transplant candidates have been tested for these antibodies, and the choice of the detection assay has become essential. Recently, the pioneer method, the complement-dependent cytotoxicity, has been integrated but has not been replaced by more-sensitive solid-phase assays, such as the enzyme-linked immunosorbent assay and the bead-based technology (ie, flow cytometry: FlowPRA, and FlowAnalyzer: Luminex).

We compared the sensitivity and antibody specificity of these 4 techniques for detecting panel-reactive antibodies in a population of 101 consecutive patients awaiting a renal transplant (which had already resulted positive in a prescreening analysis).

Sera positive for class I and class II antibodies were 62 and 90 as assessed by the complement-dependent cytotoxicity method, 76 and 58 by using enzyme-linked immunosorbent assay, 83 and 65 with Flow-panel-reactive antibodies, and 90 and 79 by Luminex. Luminex gave more positive scores than the others for class I HLA antibodies, whereas complement-dependent cytotoxicity revealed more positives for those of class II.

Although Luminex appears more efficient among these assays, our results indicate that use of multiple methods is still the best approach for characterizing the immunologic status of these patients.