Acute antibody-mediated renal allograft rejection associated with HLA-Cw17 antibody

Detection of donor-specific human leukocyte antigen (HLA) antibodies is an important part of diagnosis of antibody-mediated rejection (AMR) in the renal transplant population. Donor-specific antibodies (DSA) against HLA-C, a Class 1 major histocompatibility gene product, are not considered to be of major importance in renal transplant rejection. Typing for HLA-C is not a routine part of pre- and post-transplant evaluation. In roughly 10% of biopsy-proven C4d-positive rejections, DSA are not detected by standard testing protocols. In some of these cases, minor HLA and non-HLA antibodies have been implicated. The role of HLA-C antibodies in this patient group is not clear. We present a patient with acute renal graft dysfunction 21 months post-transplant. The allograft biopsy showed features of AMR with diffuse margination of inflammatory cells and diffuse C4d staining in peritubular capillaries. HLA-Cw17 antibody was detected by single-bead antigen Luminex assay, which was further confirmed by a mock flow crossmatch. This case highlights the importance of checking anti-HLA-Cw antibodies in patients with AMR and no detectable DSA using standard methods.