Preformed C1q-binding Donor-specific Anti-HLA Antibodies and Graft Function After Kidney Transplantation

Background: De novo complement-binding donor-specific anti-human leukocyte antigen antibodies (DSAs) are reportedly associated with an increased risk of kidney graft failure, but there is little information on preformed complement-binding DSAs. This study investigated the correlation between preformed C1q-binding DSAs and medium-term outcomes in kidney transplantation (KT). Methods: We retrospectively studied 44 pretransplant DSA-positive patients, including 36 patients who underwent KT between April 2010 and October 2016. There were 17 patients with C1q-binding DSAs and 27 patients without C1q-binding DSAs. Clinical variables were examined in the 2 groups. Results: Patients with C1q-binding DSAs had significantly higher blood transfusion history (53.0% vs 18.6%; P =.0174), complement-dependent cytotoxicity crossmatch (CDC-XM)-positivity (29.4% vs 0%; P =.0012), and DSA median fluorescence intensity (MFI) (10,974 vs 2764; P =.0009). Among patients who were not excluded for CDC-XM-positivity and underwent KT, there was no significant difference in cumulative biopsy-proven acute rejection rate (32.5% vs 33.5%; P =.8354), cumulative graft survival, and 3-month and 12-month protocol biopsy results between patients with and without C1q-binding DSAs. Although patients with C1q-binding DSAs showed a higher incidence of delayed graft function (54.6% vs 20.0%; P =.0419), multivariate logistic regression showed that DSA MFI (P =.0124), but not C1q-binding DSAs (P =.2377), was an independent risk factor for delayed graft function. Conclusions: In patients with CDC-XM-negativity, preformed C1q-binding DSAs were not associated with incidence of antibody-mediated rejection and medium-term graft survival after KT. C1q-binding DSAs were highly correlated with DSA MFI and CDC-XM-positivity.