LBP27: DECIPHERING STRONG AUTO AND ALLO HLA ANTIBODY REACTIVITIES POST ANGIOPLASTY FOR RENAL TRANSPLANT CANDIDATES

Abstract

Auto HLA antibody is a relatively common observation among renal transplant candidates, especially among patients with autoimmune disease as the cause of ESRD. Post transplant de novo auto reactivities were linked to chronic rejection and hypothesized to result from crosstalk between allo and autoimmune responses. The importance of auto antibody identified among transplant candidates remains ambiguous. Angioplasty is a common treatment option for atherosclerosis which is not rare for older renal transplant candidates. Strong auto and allo HLA antibodies post angioplasty were observed, presenting added challenge to assigning clinically relevant unacceptable antigens for virtual crossmatch. The patient’s monthly sera were analyzed by single antigen beads (SAB) with multiple attempts to reduce background including DTT treatment and post auto absorption. Auto reactivity was assessed by Auto-Flow crossmatch. Allo specificities were compared to CDC and Flow crossmatch data with surrogate donors. Ten surrogate donor crossmatches were performed utilizing cells from routine patient work-ups. This way crossmatch compatibility could be used to aid determination of unacceptable specificities. The auto reactivity by single antigen bead assay post angioplasty can be very strong and accompany other allo reactivities. We developed a process to help distinguish unacceptable antigens for patients in this circumstance. The patient serum should be analyzed with and without treatment. Auto crossmatch with the ambiguous sera should be done to validate auto reactivity. New allo antibody specificities identified at the same time as auto antibodies should be confirmed by crossmatch using surrogate cells if possible. Incorporating the patient sera into routine cell workups can allow for this insight with no extra cost. Positive surrogate crossmatch can validate the allo specificity for unacceptable listing. There are limitations to antibody identification using SAB; nonspecific binding can contribute to auto reactivity. However, simply disregarding the auto-reactivity and blindly selecting or rejecting allo specificities of similar strength is discouraged. This feasible approach to comprehensive evaluation can increase patient safety when virtual crossmatch is so widely used in the current clinical setting.