Background:

Luminex platform based solid phase antibody assays are used to identify unacceptable antigens for kidney transplant (Tx) candidates. Criteria for listing such unacceptable antigens varies across centers and importantly the relative risk of AMR associated with the strengths of DSA, as characterized by mean channel fluorescence intensity (MFI), has not been fully studied.

Methods:

We prospectively profiled 487 sera obtained at time of Tx using single antigen beads (LabScreen™ assay) and evaluated risk for AMR within the first year of Tx. DSA directed at HLA Class I (A B C) & Class II (DR DQ) were resolved & sum of MFI values were calculated for Class I (CI) & II (CII) and used to classify the study cohort into 3 groups – NO DSA, DSA MFI 1-3k and DSA MFI >3k. Only DSA MFI values >1k were used in the calculation. All individuals had a negative CDC T cell XM at the time of Tx.

Results:

Of 487 patients, 143(29%) had DSA with sum MFI>1K for either CI or CII. Patients with DSA were more likely to be females (P=0.01), AA (P<0.001), re-Tx recipient (P<0.001) and DDKTx (P=0.01) and developed DGF (P=0.02). Prior transplant and MFI sum of CI & CII DSA were significant predictors of AMR (n=26) by univariate analysis. DSA but not prior transplant was a significant predictor in a multivariable model. The risk of AMR increased significantly with MFI sum>3K.

Conclusion:

Preformed DSA is associated with increased risk AMR. Our data demonstrating that AMR increases from 2.6% in those with no DSA, to 4.4% with DSA MFI 1k-3k, and 19% with DSA MFI>3k emphasize the need for individualized therapy to forestall AMR.

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