Background: Despite prospective crossmatching and modern immunosuppression, early acute rejection is still present in cadaveric renal transplantation. The purpose of this study was to evaluate the incidence of preformed anti-donor antibodies, detected by 2 solid-phase techniques, and to analyze their impact on early renal allograft outcome.
Material/Methods: Flow crossmatch detecting the presence of anti-donor IgG and IgM antibodies was performed in pre-transplant sera of 279 patients with negative cytotoxic crossmatch. Screening for IgG antibodies detected by bead-based multiplex technique was performed in sera of 69 patients from the FCXM group. The incidence of early biopsy-proven rejection and graft failure within 3 months after transplantation was analyzed.
Results: Anti-donor IgG antibodies were detected in 33 patients (11.8%) by flow crossmatch and in 10 patients by multiplex (14.5%). IgM antibodies were detected in 23 patients (8.2%). All multiplex-positive sera were also positive for IgG by flow crossmatch, but in 18 cases no antibodies were found by multiplex technique. Biopsy-proven acute rejection within 3 months after transplantation was observed in 16 patients, and 5 allografts were lost due to immunological reasons. Presence of IgG antibodies was found to have no effect on early outcome, while the presence of IgM antibodies was associated with significantly higher rejection rate and immune-related graft failure.
Conclusions: Anti-donor IgG antibodies detected by bead-based and cell-based technique have no impact on biopsy-proven rejection rate or graft failure. Anti-donor IgM detected by flow crossmatch have significant impact on early transplantation outcome.

Keywords: flow crossmatch, alloantibodies, acute allograft rejection