Background: High levels of panel reactive antibody (PRA) have been associated with a significant risk of acute rejection and graft loss. Immunosuppression has only modestly attenuated this risk. The aim of this analysis was to determine the impact of the utilization of solid phase Luminex single antigen beads to detect HLA antibodies, virtual cross-matching using novel stringent HLA epitope analysis with protein sequence alignment CLUSLTW2 and cutoffs of >1,000 MFI on outcomes in kidney transplant recipient (KTX).

Methods: This was a sub-analysis of a single-center prospective risk stratified RCT comparing IL-2 receptor antagonist to thymoglobulin induction on clinical outcomes in KTX. Pediatrics, multi-organ transplants or those with active infection were excluded. Patients were consequently enrolled between 3/09 and 7/11.

Results: 200 patients were included in this RCT; 66 patients were significantly sensitized (PRA≥50%), 134 had a PRA<50%. Sensitized patients were more likely to be female, African American and receive a deceased donor. The sensitized group did have a non-significant trend in higher FK levels (see Figure 1, mean FK 9.3±1.4 vs. 8.8±1.3 ng/mL, p=0.076). Graft loss and death were low and similar between groups; the sensitized patients had a lower incidence of BK infection or nephropathy (bottom of Table 1). Acute rejection rates were similar between groups in those that received an IL-2RA (9% for PRA<20%, 13% PRA≥20%, p=0.489) compared to those that received Thymoglobulin (6% for both groups p=1.00).

Conclusions: High PRA, traditionally thought of as a significant risk for acute rejection, can be minimized with the use of a stringent matching protocol and advanced HLA epitope analysis.

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