P250 Reporting potential donor specific antibodies (DSAS) to aid clinicians’ choice of recipients for deceased donor kidney transplant

Aim A virtual crossmatch determines which recipients are eligible for a deceased donor kidney based on UNET unacceptable antigens. The MFI threshold for unacceptable antigens is often higher than what most labs consider to be positive (e.g. 1000 MFI). Clinicians are interested in knowing whether DSAs below the threshold are present so immunosuppression protocols can be altered or, if several are present, they should rule out a patient for transplant. What is the mechanism for reporting to clinicians the presence of potential DSAs during deceased donor kidney allocation?. Methods The Laboratory of Immunogenetics & Transplant (LIT) serves three kidney transplant centers and the local organ procurement organization. Waitlist patients are screened yearly by One Lambda Single Antigen I/II beads. Unacceptable antigen (UA) cutoffs are 3000-5000MFI, while single antigen beads >1000 MFI are assigned as positive with a few exceptions. During deceased donor evaluation, LIT technologists complete HLA-specific data entry into DonorNet and perform the matchrun. Using LIT-specific Histotrac programming, LIT runs exclusion algorithms for local protocols, choses the top candidates to crossmatch, and creates a Virtual XM report. Two centers use a protocol to avoid unacceptable antigens with additive MFIs >3000. We reviewed matchruns, virtual crossmatch exclusions, and transplants from March 2015 to Febuary 2017. Results In two years of cases, 332 kidney matchruns were evaluated: 286 local matchruns were performed while 46 import donors were evaluated. Consequently, 2288 patient-donor pairs were reviewed by virtual crossmatch. Patients were ruled out due to additive DSAs in 17 (0.7%) patient-donor pairs. Two-thirds of patients who were transplanted with a deceased donor kidney had a 0% cPRA while 5% had cPRA 98–100%. Positive virtual crossmatches prompted additional review of UA and antibody history. Conclusions The laboratory staff is responsible for completing deceased donor matchruns and generating a virtual crossmatch report, thus providing a streamlined approach to deceased donor evaluations. The virtual crossmatch report is essential for clinicians’ center-specific algorithms, induction protocols, and assessing risk for kidney candidates in the presence of potential DSA.