C1q-Fixing Human Leukocyte Antigen Assay for Chronic Antibody-Mediated Rejection in Renal Transplant Recipients
Kidney Center, Department Sugery, Tokyo Women's Medical University, Tokyo, Japan
Department of Transplant Immunology, Tokyo Women's Medical University, Tokyo, Japan
Meeting: 2013 American Transplant Congress
Abstract number: B1009
(Background)
Antibodies against human leukocyte antigens (HLAs) are associated with the antibody-mediated rejection and ultimately graft loss. The standard assays used to detect antibodies against HLAs include the cell-dependent cytotoxicity (CDC) assay, flow cytometry crossmatching (FCXM) assay, and HLA single-antigen bead (SAB) assay. However, the SAB assay is more sensitive and specific than the CDC or FCXM assay; it detects all antibodies against HLAs without differentiating between their complement-activating ability. The new “C1q assay” can detect complement-fixing HLA antibodies by using a highly sensitive and specific SAB assay technique. The aim of this study was to identify the relation between C1q-fixing HLA antibodies and graft outcome in chronic antibody-mediated rejection (cAMR) in renal transplant recipients.
(Methods)
We retrospectively studied 13 renal transplant recipients who developed cAMR and were treated with plasma exchange and rituximab. We measured the pre- and post-treatment values of IgG and C1q-fixing donor specific antibodies, and compared the pathological findings, serum creatinine levels, and graft survival between the C1q-positive (n = 7) and C1q-negative (n = 6) recipients.
(Results)
Allograft loss occurred in 3/7 patients (42.9%) from the C1q positive group, whereas no allograft loss occurred in patients from the C1q negative group. The graft function significantly improved in the C1q-negative group compared to its function in the C1q-positive group (mean creatinine levels at 32 months were 0.9 mg/dL and 5.4 mg/dL for the C1q-negative and C1q-positive group. p=0.027).
However C4d deposition on peritubular capillaries or glomerular capillaries was similar for both groups, the c score following analysis of Banff classification findings was higher in the C1q-positive group than C1q-negative group.
(Conclusion)
The results suggested that the presence of C1q-binding antibody was a risk factor for graft dysfunction and graft loss. Therefore, the C1q assay may play an important role in the assessment of graft outcome in cAMR.
To cite this abstract in AMA style:
Kai K, Tsutomu I, Yashuo M, Ogawa Y, Koyama I, Makajima I, Fuchinoue S. C1q-Fixing Human Leukocyte Antigen Assay for Chronic Antibody-Mediated Rejection in Renal Transplant Recipients [abstract]. Am J Transplant. 2013; 13 (suppl 5). https://atcmeetingabstracts.com/abstract/c1q-fixing-human-leukocyte-antigen-assay-for-chronic-antibody-mediated-rejection-in-renal-transplant-recipients/. Accessed May 14, 2025.« Back to 2013 American Transplant Congress