Chimerism Analyses

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.

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
Keywords:
Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document. Disclaimer The Haematology Department Protocols and Guidelines (the Red Book) are intended as a guide for registered health professionals to communicate guidelines and share best practices with supporting health professionals within New Zealand district health boards. They are not intended to be provided to or used as a reference for patients or non-registered health professionals. All health professionals must exercise their own clinical judgement and use pertinent clinical data when treating patients. The authors and editors of this publication have checked with sources believed to be reliable in their effort to provide information that is complete and in accord with the standards accepted at the time of publication. However, in view of the possibility of human error or changes in medical science, neither the authors, editors, publisher, nor any other party who has been involved in preparing or publishing this work warrants that the information contained in it is accurate or complete in every respect. They therefore have no liability (whether in tort (including negligence) or otherwise) for any loss or damage arising out of any reliance on this information. This publication has been compiled by the staff and contractors of Canterbury District Health Board (CDHB) and as such CDHB has copyright for this book. Amendments must be authorised in accordance with the documented process. No release of part of, or all of, this publication to any other party or organisation is permissible without the prior approval of the designated document owner.
Send Feedback Send Feedback	Expand All Drop-downs