The role of the histocompatibility laboratory in desensitization for transplantation

The ability of histocompatibility laboratories to define and monitor human leukocyte antigen (HLA)-specific antibodies via highly sensitive immunoassays has been a major contributing factor in the development of desensitization protocols for HLA-incompatible transplants. This review will focus on the laboratory's role in desensitization and the types of tests needed for determining the specificity and strength of antibodies to donor HLA pretransplant, during treatment, and after transplant.

Increasingly, solid-phase immunoassays that use purified HLA molecules are providing sensitive characterization of HLA-specific antibodies. Assay parameters, such as median fluorescence intensity, can be correlated with cross-match results and clinical outcomes, and subsequently used to monitor antibody status in patients undergoing desensitization. The strength of donor HLA-specific antibody, measured by cross-match and/or solid phase assays, is used to determine the likelihood of successful desensitization, as well as the risk of posttransplant antibody-mediated rejection.

Histocompatibility laboratories are essential components of desensitization programs. Thorough antibody characterization and serial monitoring of changes in antibody status are needed pretreatment, during treatment and after transplant. Because clinical decisions rely heavily on changes in antibody specificity and strength, desensitization should not be undertaken without access to appropriate histocompatibility testing.