Efficacy of Induction Therapy with ATG and Intravenous Immunoglobulins in Patients with Low‐Level Donor‐Specific HLA‐Antibodies

Low‐level donor‐specific HLA‐antibodies (HLA‐DSA) (i.e. detectable by single‐antigen flow beads, but negative by complement‐dependent cytotoxicity crossmatch) represent a risk factor for early allograft rejection. The short‐term efficacy of an induction regimen consisting of polyclonal anti‐T‐lymphocyte globulin (ATG) and intravenous immunoglobulins (IvIg) in patients with low‐level HLA‐DSA is unknown. In this study, we compared 67 patients with low‐level HLA‐DSA not having received ATG/IvIg induction (historic control) with 37 patients, who received ATG/IvIg induction. The two groups were equal regarding retransplants, HLA‐matches, number and class of HLA‐DSA. The overall incidence of clinical/subclinical antibody‐mediated rejection (AMR) was lower in the ATG/IvIg than in the historic control group (38% vs. 55%; p = 0.03). This was driven by a significantly lower rate of clinical AMR (11% vs. 46%; p = 0.0002). Clinical T‐cell‐mediated rejection (TCR) was significantly lower in the ATG/IvIg than in the historic control group (0% vs. 50%; p < 0.0001). Within the first year, allograft loss due to AMR occurred in 7.5% in the historic control and in 0% in the ATG/IvIg group. We conclude that in patients with low‐level HLA‐DSA, ATG/IvIg induction significantly reduces TCR and the severity of AMR, but the high rate of subclinical AMR suggests an insufficient control of the humoral immune response.