Identification of high- and low-risk second kidney grafts

The purpose of this study was to identify recipients who are at low or high risk of early cadaveric regraft failure by segregating results of the flow cytometric crossmatch (FCXM) test with previous graft survival time (PGST). Early immunologic kidney regraft failure was analyzed in 103 multicenter recipients by cross-stratifying FCXM negative/positive status with ≤3- and >3-mouth PGST. T cell and B cell cytotoxicity crossmatches were negative. All were tested retrospectively in the T cell FCXM and 60 of the 103 were also tested in the B cell FCXM. A positive T and B cell FCXM was defined as a mean channel shift of ≥9 (256 channel log scale) or ≥40 (1024 channel log scale) for pretransplant crossmatch serum above negative control serum. Recipients received triple immunosuppression therapy and limited-use antilymphocyte induction therapy. Early cadaveric regraft losses were biopsied. Comparably good rates of second kidney graft survival at 3 years were found among three low risk subsets: 78% for 18 FCXM-positive patients with PGST >3 months, 78% for 49 FCXM-negative patients with PGST >3 months, and 84% for 19 FCXM-negative patients with PGST ≤3 months. In contrast, 53% 3-month and 44% 3-year regraft survival rates occurred in 17 high-risk FCXM- positive recipients with a PGST ≤3 months. The odds ratio for increased relative risk of early second graft loss was 4.5 (confidence interval: 1.32- 16.7) for the high-risk versus low-risk subsets (P=0.009). Within the high- risk subset, 56% (5 of 9) of those who were FCXM T negative B positive experienced early regraft loss. A positive B cell FCXM has an adverse clinical impact only for high-risk regraft recipients. Pretransplant panel reactive antibody levels, pregnancy, number of blood transfusions between grafts, repeat donor HLA mismatches, and regraft-recipient HLA mismatches did not correlate with early regraft loss. We conclude that kidney regraft survival rates in low-risk recipients (PGST >3 months/FCXM negative or positive [T and/or B cell] and PGST ≤3 months/FCXM negative) approach primary graft survival rates and justify retransplantation, but the rate in high-risk regraft candidates (PGST <3 months/FCXM positive T and/or B cell) suggests that retransplantation should be performed only with a negative FCXM.