De novo donor-specific antibody (dnDSA) development is associated with late/chronic active antibody-mediated rejection (CAMR) and graft failure in low-risk kidney recipients. It has been recently suggested that kidney recipients with high level soluble B cell activating factor BAFF (sBAFF) have a higher risk of developing dnDSA, and agents that target BAFF interactions with its receptors have been proposed for the treatment of CAMR.

Aim of this study was to evaluate the role of sBAFF as adjunctive tool to help predict the outcome of pediatric kidney recipients developing dnDSA, and reinforce a rationale for the use of anti-BAFF antibodies for the prevention of CAMR. Utilizing sera collected three-monthly in the first year, and annually thereafter, we retrospectively evaluated 81 consecutive primary pediatric kidney recipients grafted between 2003-2010 and with a minimum follow-up of 18 months, for de novo occurrence of HLA-antibodies by Luminex screening kit and single-antigen analysis. On the same samples, sBAFF was quantified by a commercially available ELISA assay.

At a median time of 52 months, 23 patients developed dnDSA, and 24 dnNDSA. In all patients, a significant, progressive increase in the levels of sBAFF was observed in the first posttransplant year. Patients with dnDSA had significantly higher levels of sBAFF (median: 581 vs 510 pg/ml in pts with NDSA or Ab-negative; p<0.005). Within the DSA cohort, patients who developed CAMR had significantly higher pre-CAMR sBAFF levels (median: 929 vs 574 pg/ml throughout follow-up in pts who did not develop CAMR). Interestingly, DSA pts developing CAMR showed a significantly higher percent increase in sBAFF at DSA development (median % increase pre-DSA-DSA onset 34% vs -1% in the DSA pts who did not progress to CAMR, p=0.05). In our pediatric kidney recipients, DSA and sBAFF monitoring identify a cohort at risk of CAMR.

Our data suggest that treatment started at the time of antibody emergence, perhaps with anti-BAFF antibodies, might prevent CAMR occurrence and/or progression to graft failure.

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