Clinical significance of post kidney transplant de novo DSA in otherwise stable grafts.

We have previously shown poor outcomes in a cohort of kidney recipients with de novo donor specific anti-HLA antibodies (DSA) detected via post-transplant screening, were due to prior acute rejection (AR) episodes. In this report, we sought to identify DSA characteristics associated with poor outcomes in the absence of AR. All living and cadaveric donor kidney/ kidney-pancreas recipients from 9/07 to 10/09 were screened for class I and II DSA at 1, 6, 12, and 24 months post-transplant, in addition to whenever clinically indicated, using single antigen beads and Luminex technology. Mean florescence intensity (MFI) > 500 was defined as positive. Compared to DSA(-) patients, those who developed both class I and II DSA experienced worse graft survival (p < .001). Graft survival in those with class I or II alone was unchanged. Patients with DSA MFI > 6000 experienced worse 1-year modification of diet in renal disease glomerular filtration rate (MDRD GFR) (p = 0.022) and 2-year graft survival (p = .026) compared to DSA(-) patients, whereas graft survival in groups with lower antibody strength was not statistically different. The effect of DSA class and strength was lost when removing patients with AR from the analysis. In sum, with a mean follow-up of 29 months, the presence of combined de novo class I and II DSA as well as DSA with MFI > 6000, is associated with worse graft outcomes only in association with AR episodes.