The role of positive flow cytometry crossmatch in late renal allograft loss.

ABSTRACT

Many studies relating flow cytometery crossmatch (FCXM) results to kidney transplant outcomes have examined risk in the first 3 to 12 months. We used Organ Procurement and Transplant Network registry data for 66,594 kidney transplants from 1995 to 2007 to investigate associations of T-cell positive (T+) and T-cell negative/B-cell positive (T(-)B+) FCXM with graft failure risk early (years 0-1) and late (years >1-5) after transplant. Compared with transplants with T-cell negative/B-cell negative (T(-)B(-)) FCXM, living-donor transplants performed after T+ FCXM had significantly higher adjusted, relative risks of both early (adjusted hazards ratio [aHR] 1.71, p < 0.0001) and late (aHR 1.36, p = 0.017) graft loss. T(-)B+ FCXM was associated with approximately 40% higher relative risk of graft loss in the late period only. Patterns were similar for deceased-donor transplants. The risks of positive FCXM persist beyond the peritransplant period for years after transplant. Damage by memory effector cells may explain the long-term risks associated with positive FCXM.