6-OR: MULTIPLE TEST METHODS FOR PROGNOSTIC IDENTIFICATION OF CLINICALLY-SIGNIFICANT ANTI-HLA ANTIBODIES

Aim Identification of DSA can be problematic due to antigen saturation in some patients. It is important to identify supplemental methods in order to accurately assess immunologic compatibility. This case demonstrates the utility of sample dilution and the C1qScreen assay (C1q) in providing additional information to accurately assess anti-HLA antibodies (Ab) in a highly-sensitized patient. Methods Patient serum was tested for anti-HLA Ab by Luminex Single Antigen (LSA) and C1q. Serum was tested neat and diluted 1:25. Crossmatch was performed by antihuman globulin-augmented complement-dependent cytotoxicity (AHG). Results Pre-transplant (Tx) LSA identified numerous Class I and II Ab (cPRA = 100). The patient received a lung Tx across known DSA with a strongly positive AHG, T-cell and B-cell positive to 1:512. The patient underwent aggressive immunosuppression and plasma exchange, resulting in stable graft function. Retrospective testing of pre-Tx serum by LSA at 1:25 dilution, and C1q, demonstrated strong DSA. Evaluation on post-op day 52 demonstrated reduced overall anti-HLA Ab with persistent Class II DSA (cPRA = 95) by LSA, not seen on C1q testing. Post-op day 261 showed the first evidence of no DSA by LSA, with continued graft function. Conclusions Prognostic identification of clinically-relevant Ab may require multiple test methods. Ab identified by C1q may more accurately reflect post-Tx compatibility [ Table 1 , Table 2 ].