Pre-transplant donor specific anti-HLA antibody is associated with antibody-mediated rejection, progressive graft dysfunction and patient death.

The long term effect of donor specific antibodies (DSA) detected by Luminex Single Antigen Bead (SAB) assay in the absence of a positive complement-dependant cytotoxicity (CDC) crossmatch is unclear. DSA at the time of transplant were determined retrospectively in 258 renal transplant recipients from 2003 to 2007 and their relationship with rejection and graft function prospectively evaluated. After a median of 5.6 years follow-up 9% of patients had antibody mediated rejection (AMR) (DSA 11/37 (30%), DSA-Neg 13/221 (6%), HR 6.6, p<0.001). Patients with anti-HLA class II (HR 6.1) or both class I+II (HR 10.1) DSA had the greatest risk for AMR. The Mean Fluorescent Intensity (MFI) of the DSA was significantly higher in patients with AMR than those with no rejection (p=0.006). Moreover, the strength of the antibody was shown to be important, with the risk of AMR significantly greater in those with DSA >8000 MFI than those with DSA <8000 MFI (HR 23, p<0.001). eGFR progressively declined in patients with DSA but was stable in those without DSA (35.7 ± 20.4 mls/min vs 48.5 ± 22.7) and composite patient and graft survival was significantly worse in those with class II (HR 2.9) or both class I+II (HR 3.7) but not class I DSA. Class II DSA alone, or in combination with class I DSA had the strongest association with graft loss and patient death. Patients with DSA not only have increased rates of acute AMR, but also chronic graft dysfunction, graft loss and death. Antibody burden quantified by SAB assay may identify patients at highest immunological risk and therefore influence patient management and improve long-term patient outcome.