Presence of DSA, including to HLA-DP, in stem cell transplant patients has been associated with lower levels of engraftment using bone marrow and peripheral blood stem cells (only 30-40%) and using cord blood (60-70%).

The cut off for positive reaction on Luminex varies between centres but typically, an MFI above 1,500-2,000 would be considered positive. A patient who has DSA against a potential donor mismatch but where the MFI is below the cut off would not be considered a contraindication to transplant though the transplant team would be informed of the presence of potential DSA and antibody monitoring will be carried out in the weeks leading up to transplant. If the patient is having platelet transfusions it would be advisable to use HLA matched platelets to avoid further sensitisation though this does have a cost implication.

Presence of DSA above the positive cut off would generally be considered a contraindication to standard transplant protocols. Data on desensitisation protocols with such transplants is limited though a few successful transplants have been performed with a variety of antibody reduction protocols such as IvIG and Rituximab.

Post-transplant engraftment monitoring is vital in all transplants which take place in the presence of DSA irrespective of MFI levels. Days to neutrophil and platelet count engraftment must be tracked closely and chimerism testing must be undertaken at least monthly. Post-transplant HLA antibody levels should also be monitored.