Q1 – 3: Chimerism Studies

Chimerism studies are performed to determine the percentage of blood or marrow cells post-infusion produced from donor hematopoietic stem cells and the percentage produced from host (recipient) hematopoietic stem cells.

*Appendix C: Cytogenetics
Refer to Chimerism and Cytogenetics found in Appendix C: Cytogenetics for additional information, including the different types of chimerism methods of assessment.

Different types of blood cells and a variety of laboratory tests can be used to determine if a chimera (presence of both donor- and host-derived cells) exists. If cytogenetic testing was performed to look for disease markers, and the donor and recipient are of different sexes, the test may also be used to determine if a chimera exists. If the donor and recipient are of the same sex, cytogenetic testing using the common staining technique, known as giemsa banding (G-banding), cannot be used to determine if there is a chimera. However, quinicrine banding (Q-banding) can be used to identify if the cells are of donor origin or not in a same-sex transplant, as this staining technique highlights inherited chromosome polymorphisms on certain human chromosomes including 3, 4, 13, 15, 21, 22, and Y. This is not a commonly used staining technique and is only helpful when the polymorphism is documented pre-infusion.

*Failed Chimerism Studies
If chimerism studies were attempted, but no evaluable results were obtained, do not report the test.

*Multi-Donor Chimerism
When multi-donor chimerism exists and includes a donor (or donors) from a prior infusion, report the results as a multi-donor chimerism though there may only be one donor for the current infusion.

*Reporting Multiple Chimerism Studies
If multiple chimerism studies were completed on different dates in the reporting period, complete all chimerism questions for each chimerism study by adding an additional instance in the FormsNet3^SM application. Ensure the minimum chimerism results are reported (see below).

Question 1: Date sample collected

Report the date when the sample was collected for the chimerism test. If the exact date is unknown, use the process described in General Instructions, General Guidelines for Completing Forms for reporting estimated dates.

Chimerism Studies Required to be Reported

Transplant centers may perform frequent chimerism studies. If there is a need to reduce the number of chimerism study results reported due to volume, ensure that the following are reported at a minimum:

• Studies performed on or at approximately Day 30
• Most recent studies performed prior to or on the date of contact for the Day 100, Day 180, and Day 365 timepoints, if applicable
• Most recent studies performed prior to and after an intervention (such as a DLI)

Questions 2 – 3: Cells tested (check all that apply)

For the date of the chimerism study reported above, select all cell types assessed.

• Unsorted bone marrow: The specimen is bone marrow but was not sorted for a specific cell line.
• Unsorted peripheral blood: The specimen is peripheral blood but was not sorted for a specific cell line.
• T-cells: Includes CD3+, CD4+, and / or CD8+ cells.
• NK cells: Includes CD56+ cells.
• Red cells: Also known as RBCs or erythrocytes. Includes CD71 cells.
• Other: If the cell type does not fit in any of the above options, specify the cell type. Includes, but not limited to hematopoietic progenitor cells (includes CD34+ cells), total mononuclear cells (contains only and both lymphocytes and monocytes), granulocytes (also known as polymorphonuclear leukocytes and includes neutrophils, eosinophils, basophils, and CD33+ cells).

*Reporting Multiple Chimerism Studies
CIBMTR strongly encourages attaching the chimerism study results.

*Donor Identifier
The donor identifier column will auto populate with the donor identifier information.

!Incorrect Donor Identifier Information
If the auto-populated donor identifier information is incorrect, update the donor information section of the Pre-TED (2400) with the correct data.

Chimerism study results

For each cell type assessed, specify the donor chimerism result(s) as a percentage, to the nearest whole number. If the chimerism method is karyotyping or FISH (only applicable when the donor and recipient are sex mismatched), convert the results to a percentage.

When reporting donor chimerism percentages for each cell type, individual donor values must not exceed 100%. In cases with multiple donors, the combined chimerism percentage for all donors and the recipient must not exceed 100% per cell type.

Section Updates

Question Number	Date of Change	Add/Remove/Modify	Description	Reasoning (If applicable)

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