Utility of HLA antibody testing pretransplant
Waitlist testing for HLA antibodies
Testing for HLA antibodies while waitlisted or during transplant workup serves to identify transplant candidates with potentially reduced access to acceptable donors by virtue of preexisting HLA antibodies acquired through pregnancy, transfusion, or prior transplant. The panel reactive antibody serves as an estimate of the percentage of potential donors to whom a recipient will have donor-specific HLA antibodies (with corresponding risk of a positive crossmatch). Beyond application of panel reactive antibody in quantifying transplant access for patients and and care providers, those patients with the highest panel reactive antibody (and lowest access to acceptably mismatched donors) may be prioritized in allocation schema to improve equity of transplant access. Because antibody levels and specifities wax and wane over time, repeated testing (usually 3-12 times per year depending on regional regulations) is performed to obtain the most comprehensive immunologic profile. Even if transient, detected antibodies may represent potential for future immunologic memory responses if targeted to donor antigens and affect subsequent risk assessment.