*Purpose: To evaluate development of de novo donor specific antibodies (dnDSA) in Renal Transplant Recipients (RTR) with immunosuppression (IS) modulation due to BK viremia (BKV) and the associated risk of antibody mediated rejection (AMR).

*Methods: We retrospectively collected data from the NM Enterprise Data Warehouse, primary review of biopsies and HLA antibody testing on all RTR 2007-2017 at our center (n=1911). BK case group included pts who develop BKV >10,000 c/ml or biopsy proven BKV and nephropathy (BKVN). DSA and biopsy reports through 1 yr post-dx were included in the analysis. Two matched controls without BKVN or BKV were selected for each case. Controls were matched by gender, donor type and transplant within 1 yr. For BK group, dnDSA was defined as detected only after IS modulation. Per protocol, MMF was reduced initially at the direction of the transplant nephrologist.

*Results: 248/1911 RTR (12.9%) had BKV or BKVN. Of these, 37 (14.9%) developed dnDSA during the 1 yr follow up, with 36/37 (97.29%) developing the dnDSA within 1 yr of tx. Among control group, 37/239 (15.48%) exhibited dnDSA, with the majority of DSA (64.87%) occurring > 1 year post-tx. AMR was diagnosed in 17/203 (8.4%) biopsied BK and 37/445 (8.3%) biopsied control pts. All 17 AMR+ BK pts developed AMR within 1 yr of BK diagnosis (median=143 days). In contrast, 21/37 (56.75%) of control pts developed AMR >1 yr post-tx (median=463 days).

*Conclusions: nDSA developed after IS reduction for BKVN in a minority of pts but is associated with a risk of AMR. While rates of dnDSA and AMR were similar between cases and controls, dnDSA and AMR was more likely to occur within the 1^st yr post-transplant in the BK cases. Further data is needed to determine the rate of dnDSA and AMR in pts with and without BK.

« Back to 2020 American Transplant Congress