The role of complement-fixing donor-specific antibodies identified by a C1q assay after heart transplantation.

BACKGROUND

The development of donor-specific antibodies (DSA) to human leukocyte antigens (HLA) has been associated with acute rejection and allograft failure after heart transplantation. Not all DSA, however, can fix complement.

METHODS

To determine the association between complement-fixing DSA and heart transplant outcomes, we retrospectively analyzed results obtained using the C1q solid-phase assay that specifically detects complement-fixing DSA in parallel with the standard IgG assay in 121 adult heart transplant recipients.

RESULTS

The 52 recipients who developed post-transplant DSA had a higher incidence of acute cellular rejection (58% vs 19%, P < .001) and antibody-mediated rejection (29% vs 7%, P < .001) than the 69 recipients without DSA. The 24 recipients with C1q+ DSA had more antibody-mediated rejection than the 28 recipients with C1q- DSA (46% vs 14%, P = .012), but there was no difference in the incidence of acute cellular rejection between these two groups. Patients with post-transplant DSA had higher mortality than patients with no DSA (29% vs 13%, P = .031), mainly due to increased incidence of acute rejection. No differences in survival were found between recipients with C1q+ DSA and C1q- DSA.

CONCLUSIONS

Routine monitoring of DSA post-transplant, and their characterization using the C1q assay, may provide prognostic information for acute rejection after heart transplantation.