Expansion of Humoral Donor-Specific Alloreactivity After Renal Transplantation Correlates With Impaired Graft Outcome

IgG human leukocyte antigen (HLA) antibodies were investigated retrospectively after transplantation in 264 primary renal graft recipients. All patients who developed de novo donor-specific antibodies (DSA) and non-DSA (NDSA) (n = 40, 15.1%) were divided into two groups. Group A consisted of patients (n = 20) with stable good graft function (GGF), and group B consisted of patients (n = 20) who developed rejection and/or graft failure (R/GF). DSA were detected in 23 patients (57.5%). Expansion of humoral alloreactivity with the presence of DSA to more than one graft mismatched antigens and coexistence of HLA class I and II DSA were significantly correlated only with R/GF (p = 0.01). Limitation of alloreactivity to one graft-mismatched antigen was detected mainly in patients with GGF. HLA-DQ DSA alone was found only in patients with GGF (p = 0.1). No significant differences were found between the two patient groups with NDSA. Expansion of the humoral alloreactivity to more than one graft molecule in renal transplant recipients identifies patients at high risk of rejection or graft failure. Limitation of humoral alloreactivity to one graft antigen perhaps associates the presence of regulatory mechanisms with GGF only in specific cases.