Evidence of Engraftment

Evidence of engraftment is usually seen within 3 weeks following stem cell transplantation and is identified as follows.

Direct Evidence

1. Fluorescence in situ hybridization (FISH) in sex-mismatched transplantation

2. Variable number of tandem repeats (VNTR) in same-sex-matched transplantation

3. HLA typing: mismatched transplantation

4. Donor-type red cell antigens

5. Immunoglobulin allotypes of donor

6. In severe combined immunodeficiency disease (SCID): the presence of adeno-sine deaminase (ADA) in white blood cells.

Indirect Evidence

1. Aplastic anemia and leukemia:

a. Adequate bone marrow cellularity b. Increase in white blood cells with normal morphology and increase in platelet counts

2. SCID: improved immunologic parameters.

Causes of Failure to Engraft

• Increased genetic disparity

• T-cell depletion or GVHD prophylaxis

• Inadequate stem cell dose

• History of multiple transfusions in aplastic anemia

• Disordered microenvironment in storage disorders and osteopetrosis.

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