I don't know what would exclude a donor - but maybe Jill knows.
This is regarding IVIG - intravenous immunoglobulin -
http://www.uspharmacist.com/index.asp?show=article&page=8_1242.htm - it's from 2004 but I believe it's accurate.
Candidate Screening
Use in Living Donor Transplantation: Cedars-Sinai Medical Center recently started an NIH-funded protocol using IVIG to lower antibodies in ESRD patients. To be eligible, patients must have a living donor and a negative in vitro IVIG crossmatch. The in vitro IVIG crossmatch is performed by adding IVIG to the patient's serum in a 1:1 dilution. Patients whose in-vitro IVIG crossmatches show inhibition are given a dose of IVIG 2 g/kg (maximum of 140 g) every month, up to four doses, given on dialysis. A repeat crossmatch is done after each infusion, and if the crossmatch becomes negative, then the transplantation proceeds. We have referred more than 60 living donor transplants with this protocol. Our initial data on 42 transplants was recently published.15
Cadaveric Transplant: Patients awaiting a cadaveric transplant are candidates for the Cedars-Sinai IVIG protocol if they have been on the UNOS list for more than five years, do not have acceptable living donors, have consistently had positive crossmatches to cadaveric organs, and have an in-vitro IVIG crossmatch test that shows inhibition by IVIG. These patients receive 2 g/kg of IVIG while on dialysis once per month for four months. Following this regimen, they are again tested for a crossmatch, and if a crossmatch-negative kidney is found, they receive the transplant.
Poor Responders: IVIG therapy is not effective 100% of the time. High-risk patients who do not achieve a low PRA score with the IVIG crossmatch, or whose PRA does not drop following IVIG pretreatment, may require plasmapheresis/IVIG treatment for a successful transplant.