Clinical relevance of low levels of preformed alloantibodies detected by flow-crossmatch in deceased kidney transplant

Abstract

Objective: To evaluate the clinical relevance of preformed alloantibodies detected by flow crossmatch, and to identify subgroups who could benefit from such evaluation in the first year follow-up after kidney transplant. Patients and Methods: Deceased kidney transplants (n=157) performed after negative microlymphocitotoxicity crossmatch against T and B lymphocytes were studied. Previously analyzed sera were retested through flow. Clinical outcomes included: primary non-functioning graft (n=14; 8.9%), delayed graft function (n=107; 68.1%), acute rejection (n=68; 43.3%), graft loss (n=25; 15.9%), death (n=16; 10.2%), graft survival in the first year. Graft function was measured by serum creatinine. Subgroups included: pre-sensitized (n=24); diabetics (n=29), simultaneous kidney-pancreas (n=22), expanded donor criteria recipients (n=55), hipersensitized (n=8), retransplants (n=8). Qui-square, exact Fisher’s, Student’s t tests and Kaplan Meier method were employed. P values >0.05 in bivariate and >0.10 in interaction (Cochran-Mantel-Haentzel) analysis were significant. Results: There was 30% of negative microlymphocitotoxicity (n=47) against T, and 36% (n=56) of B positive patients were revelled through flow. Negative and positive-flow patients were similar concerning general characteristics and clinical events. Presensitized positive-flow patients had higher creatinine (2.0+0.7 x 1.3+0.3 mg/dl; P=0.020) and lower first year graft survival (43% x 80%; P=0.074) than presensitized negative-flow patients. Presensitization and positive-flow interaction was statiscally significant concerning graft loss (OR=9.1; P=0.098) and death (OR=12.1; P=0.088). Remaining groups had no benefit from flow analysis. Conclusion: Presensitized patients have higher creatinine, graft loss and death risks in the first year when transplanted after a positive flow crossmatch.