Clinical implications of flow cytometry crossmatch with T or B cells in living donor liver transplantation

Background: Acute allograft rejection (AR) in solid organ transplantation i s generally regarded to develop through cell-mediated immune response follo wing activation of helper T cells. Since production of antibodies is also m ediated by helper T cells, humoral immunity may play some roles in AR. Alth ough flow cytometry crossmatch (FCXM) is reported as a useful method for th e detection of antibodies against donor antigen, specific role of T- or B-c ell FCXM and its sensitivity for AR is controversial. Methods: T- and B-cell FCXM using fresh donor peripheral lymphocytes were p erformed before and after blood-type compatible living donor liver transpla ntation in 47 patients. IgM and IgG antidonor antibodies were analyzed in r elation to clinical AR. Results: Positive pre-transplant T-cell FCXM was associated with a high inc idence of positive post-transplant T-cell FCXM (p = 0.017). Four of five ca ses (80%) with positive pre-transplant T-cell FCXM experienced earlier AR ( day 8.0 +/- 4.4, mean +/- SID) than 16 of 42 cases (31%) with negative pre- transplant T-cell FCXM (17.3 +/- 6.8; p = 0.016). In addition, higher dose of steroids was given to treat AR episodes in cases with positive pre-trans plant T-cell FCXM (79.9 +/- 10.3 mg/kg/month) than in those with negative p re-transplant T-cell FCXM (47.1 +/- 26.6; p = 0.039). In the first month af ter transplantation, 13 episodes of positive post-transplant T-cell FCXM we re all concomitant with or preceded clinical AR compared with seven ARs in T-cell FCXM-negative cases (p < 0.0001). T-cell FCXM between positive sera and third parties revealed some crossreactions. In contrast, detection of a ntibodies by B-cell FCXM in pre- and post-transplant phases was scarcely as sociated with AR, and no correlation was found between T and B-cell FCXM be fore and after transplantation. Conclusions: Positive T-cell FCXM is closely related with AR and that befor e transplantation is a predictor of early and refractory AR as well as post -transplant FCXM. In contrast, not a few detections of antibodies irrelevan t to AR are observed in B-cell FCXM, suggesting its low specificity.