Role of DQ donor-specific antibody in antibody-mediated rejection in renal transplant recipient: A case study.

The human leukocyte antigen (HLA) matching plays an important role in determining the clinical outcome of renal transplantation. The development of donor specific antibodies (DSA) against HLA is associated with antibody mediated allograft tissue injury, poor outcome and rejection. The DQ-DSA develops in a denovo pattern and its unfavorable impact on renal transplantation has not yet been widely reported. We investigated the clinical significance of DQ-DSA in a patient diagnosed with hypertension, CKD stage V on maintenance hemodialysis (MHD) for second renal transplant. The histocompatibility workup before the first transplant included low resolution HLA-A, B, DR typing of both patient and donor. HLA type of the patient was HLA-A29, 68, HLAB44, 44, DRB107, 11. HLA type of the donor was HLA-A03, 68, HLA-B39, 44, DRB107, 10 with a 3/6 match. The HLA antibody screen and complement dependent cytotoxicity crossmatch (CDC) were found to be negative. No therapeutic plasma exchanges (TPE) were done during stay and post-transplant the patient was on triple immunosuppressant therapy. After four years the patient was diagnosed with recurrent membranoproliferative glomerulonephritis and second renal transplant was planned, therefore, histocompatibility workup was initiated. HLA antibody screen was found to be positive for HLA class II. Initially only HLA-A, B, DR typing was performed and that too only low resolution, further, high resolution HLA typing was done for HLA-DR and DQ to rule out if these antibodies are de-novo DQ/DR DSA. We analyzed that the patient had developed de-novo DSA against HLA-DRB1* 10:01 (DR10), MFI-2374 and DQB1*06:01 (DQ6), MFI-15315. This study suggests the role of DQ antibodies in determining the graft survival and to highlight the need of HLA DQ typing as a routine of the diagnostic work-up in a solid organ transplant.