Canterbury DHB


Chimerism Analyses

The achievement of full donor chimerism is crucial to a successful outcome.

The post transplant chimeric analysis status is central to the establishment of a successful allograft in RIC SCT. Donor and patient neutrophils and CD3 positive T cells need to be identified so that the degree of engraftment can be assessed.

Short tandem repeat (STR) analysis will be used to quantitate chimerism. The same assay should be used in a given patient for repeated studies of chimerism. For sex mismatched transplants, FISH could be used, but our aim is to use STR analysis for all patients.

Mixed chimerism is commonly defined as the detection of donor T cells (CD3+) between 1% and 95% of the total T-cell population but lower levels, e.g. 2% of host T-cells may be taken as mixed chimerism if the assay used is sensitive at this level. Split chimerism refers to one or more whole lineage is host and one or more lineage is donor.

Failure of engraftment is commonly defined as the absence of detectable donor cells in the marrow and peripheral blood on day +56.

Chimerism studies are recommended at 1, 3, 6 months after T-cell depleted, non-myeloablative and reduced intensity conditioning. Consideration may be given to more frequent measurement e.g. days +28, 56, 90, 180 to predict either GVHD or graft loss. They will need to be done after day +180 under certain circumstances, e.g if DLI is given for mixed chimerism.

For further details and indications for Donor Lymphocyte Infusions (DLI), see Post Transplant Donor Lymphocyte (DLI) Procedures.

Note: Once lymphocyte engraftment has reached >95%, further chimerism studies are usually not required.

About this Canterbury DHB document (9585):

Document Owner:

Andrew Butler (see Who's Who)

Last Reviewed:

December 2016

Next Review:

December 2018


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Topic Code: 9585