Use of SEOPF regional crossmatch trays to share kidneys for sensitized patients. Local experience of three centers

Regional organ procurement (ROP) crossmatch trays are used by members of the South-Eastern Organ Procurement Foundation (SEOPF) to facilitate sharing of cadaver kidneys for highly sensitized patients. ROP trays carry a single representative serum sample from over 900 patients with panel reactive antibody (PRA) levels of greater than or equal to 60%. Trays are centrally prepared periodically and distributed to member laboratories where they are used for preliminary crossmatching against locally obtained donors. Crossmatching results are used in conjunction with the SEOPF computer match program for sharing of kidneys. Proficiency testing studies by the 40-member laboratories show a greater than 90% concordance rate on results with these highly and broadly reactive sera. Data were available from 3 centers on 74 kidneys shared between SEOPF-member institutions on the basis of a remote, preliminary, negative ROP tray crossmatch. Of these, 44 (59%) crossmatched negative locally with the same and other sera, and were thus considered acceptable to be transplanted to the intended highly sensitized patients. Sixteen (22%) donors had a positive crossmatch locally, but with sera other than that present on the ROP tray used for screening. In 14 cases (19%) the same serum as on the ROP tray gave a positive crossmatch. The majority of ROP tray inconsistencies appeared to be due to use of more sensitive crossmatching techniques at the recipient center. Of the 27 patients transplanted at these 3 centers with kidneys received on the basis of ROP tray results, none experienced hyperacute or early irreversible rejection and actual graft survival at 6-48 months is 74%. These studies indicate that regional sharing of patient sera by the existing network of histocompatibility testing laboratories is an effective and reliable mechanism to identify crossmatch-negative donors for highly sensitized patients.