Blood support for ABO incompatible stem cell transplants can be tricky. Listen as Dr James Griffin discusses the theory behind blood component support with Suzy and explains how to minimise the risks for patients undergoing ABO incompatible stem cell transplantation.

Dr James Griffin

Learning points:

ABO mismatched stem cell transplants are frequently undertaken. Blood component support is key and outcomes of the transplant overall are generally no worse.

Major mismatch: donor with antigen on their red cells that the recipient does not possess.

Minor mismatch: donor with antibodies in their plasma that the recipient has corresponding antigens to.

Anti A and anti B titres do not wholly predict for outcomes but high levels (>1:128 – 1:256) can predict complications. For donors with high titres and a minor mismatch, plasma reduction of the stem cell product may be undertaken. For recipients with high titres, plasma exchange, immunoadsorption and rituximab have all been used to reduce the levels although there is no clear evidence to support these practices.

Umbilical cord blood transplants may be tridirectional. Passenger lymphocytes and passive transfer of haemagglutinins are less of a problem. Chimerism is important to guide blood component

Reduced intensity transplants may lead to mixed chimerism, where dual blood groups may persist for a long time.

It is important to consider haemolysis in the post transplant period as a differential diagnosis of hyperbilirubinaemia.

From the time of stem cell infusion, EBMT recommend “universal” group O red cells until engraftment, and group A platelets and AB plasma. However where either the patients or donor is AB, alternative groups can be used (see link below for NHSBT guidance).

Engraftment is defined as a negative DAT and “clean” grouping i.e. no mixed field and no discrepant haemagglutinins.

Mismatched D transplants: D negative red cells and platelets should be used from the time of stem cell infusion, life-long in the instance of a minor mismatch and until there are D positive cells detectable on the forward group in the instance a major mismatch.

Useful links

NHSBT guidelines on selecting appropriate blood products for recipients of ABO/Rh mismatched stem cell transplants