SIGNIFICANCE OF B-CELL FLOW CYTOMETRIC CROSSMATCHING IN TACROLIMUS TREATED RENAL ALLOGRAFT RECIPIENTS

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308 Aim: A pretransplant positive (+) flow cytometric crossmatch (FCXM) is associated with early allograft failure in cyclosporine (CSA) treated kidney transplant (KTx) recipients. Enhanced immunosuppression (IS) may prevent these early failures. We therefore analyzed our initial experience with tacrolimus (FK) in FCXM (+) cadaveric KTx and compared with CSA treated recipients. Methods: 167 consecutive cadaveric KTx performed between 1995 and 1998 were studied. All pts had a negative (−) Amos one-wash T-cell XM. IS included steroids, ATGAM, and CSA (between 1995-1997), or FK (between 1997-1998). The pts were divided into 4 groups by FCXM status and IS regimen. Actuarial graft survivals were determined by the Kaplan-Meier method and curves were compared by log rank with a p value of <0.05 considered significant. Results: The groups were comparable with respect to recipient age, sex, race, PRA, mean HLA mismatches, retransplant status, and donor variables. Follow up was 20-46 months for CSA recipients and 1-20 months for FK. (Table) Graft survival in CSA FCXM (+) pts was significantly diminished compared to CSA FCXM (−) recipients. FK treated patients experienced equivalent success rates in FCXM (+) and (−) groups. Although follow-up is limited to 20 months in FK treated patients, early failures associated with (+) FCXM were reduced with FK treatment. It is unknown weather this will remain true over the long term.TableConclusion: We conclude that a (+) B cell FCXM has no detrimental impact on early outcome in FK treated cadaveric renal allograft recipients. Selecting recipients based on FCXM denies many patients potentially successful KTx. An intensified IS regimen may achieve satisfactory results despite the presence of low level donor-reactive antibodies detectable by FCXM.