Laboratory Medicine Division

Post-Transplant Engraftment Monitoring

Chimerism Testing

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Purpose

Hematopoietic chimerism, the ratio of recipient to donor cells, is essential for monitoring engraftment of donor cells to assess graft failure or relapse of disease after allogeneic stem cell transplantation (SCT). Serial analysis of chimerism enables determination of the trend of engraftment over time.

Full chimerism refers to a recipient with exclusively donor hematopoietic cells post-transplant. Mixed chimerism (which can be classified as transient, stable, or progressive) describes the presence of both recipient and donor hematopoietic cells.

CPT Codes

  • 81265, 81266 - First chimerism test for pre-transplant
  • 81267 - Post-transplant chimerism
  • 81268 - Each additional lineage

Methodology

Short tandem repeat loci/capillary electrophoresis (STR/CE) is routinely used for post-transplant documentation of the donor/recipient origin of white blood cells in peripheral blood and/or marrow. Engraftment analysis may include testing lineage-specific cell subsets, such as donor CD3 positive T-cells and CD56 positive NK cells which provide a favorable immunological environment for hematopoietic stem cell engraftment.

Collection Requirement

  • Pre-Transplant Patient and Donor Samples*:
    • Archived DNA – DNA will be made available from prior HLA genotyping testing during the pre-transplant evaluation.
    • Archived peripheral blood leukocytes (PBL) – If DNA of pre-transplant patient and donor is not available, previous frozen PBL can be obtained from prior HLA genotyping testing during the pre-transplant evaluation.
  • Patient Post-Transplant: Routine Samples
    • 1-3 ml Bone Marrow aspirate, anticoagulated with EDTA.
    • 1-10 ml Whole Blood anti-coagulated with EDTA.
    • Non-Routine Samples
    • 20-50 ml Whole Blood for samples with low white blood cell counts (WBC less than 1000/microliter) anti-coagulated with EDTA.
    • 20-50 ml Whole Blood for B-cell, T-cell, granulocyte, NK enrichment fractions anti-coagulated with EDTA.
    • Lineage isolated fraction containing at least 5,000 cells.
    • *Donor and recipient are tested as necessary informative references.

Storage/Transport Temperature

Transport immediately at room temperature to the laboratory. Do not refrigerate.