Cumulative mean fluorescent intensities of HLA specific antibodies predict antibody mediated rejections after kidney transplantation.

It is still not fully elucidated which pretransplant donor-specific HLA antibodies (DSA) are harmful after kidney transplantation. In particular, it needs to be clarified whether cumulative mean fluorescence intensities (MFI) against multiple HLA specificities have a predictive value for allograft function. Our retrospective single centre study analyzed preformed HLA antibodies determined by Luminex™ Single Antigen Bead (SAB) assay, including C1q addition, in relation to rejection and clinical outcome in 255 cross match negative kidney allograft recipients. Only 33 recipients (13%) of the total cohort showed early AMR during the first year posttransplant, but in patients with pre-transplant DSA the rate was increased to 15 out of 40 (38%). Three year graft survival was significantly shorter in patients with histological signs of AMR compared with patients without AMR or with no biopsy (74%, 92%, and 97%, respectively, p < 0.0001). In patients with HLA-DSA, a cumulative MFI value of all HLA antibodies of more than 103.000 indicated the highest risk for AMR posttransplant (p = 0.01). In conclusion, in patients with HLA-DSA, the cumulative MFI value may help to further stratify the risk of AMR after kidney transplantation.