CliniMACS CD34 Reagent System was FDA approved for clinical use; therefore, patients were treated clinically.

The purpose of this study is to determine if infusing additional special donor cells will help to improve graft or immune function in previously transplanted children with immune deficiencies and bone marrow failures.

The purpose of this study is to investigate the usefulness of infusing purified CD34+ cells of donor origin in order to augment graft function in response to declining chimerism after initially performing an allogeneic hematopoietic stem cell transplant (HSCT) for children with primary immunodeficiency diseases. This protocol will be utilized for patients with waning mixed donor chimerism that is inadequate for correction of clinical condition or disease for which stem cell transplant was performed, or for augmentation of immune function. An infusion of selected CD34+ stem cells will be given without any preparative regimen. As the children eligible for this protocol have reduced immune function and pre-existing donor chimerism, we hypothesize that stem cells will be able to engraft and the infusion will augment graft function. This therapy serves as an alternative to a second stem cell transplant that is known to be associated with significant morbidity and mortality. CD34+ stem cells will be collected from the donor used for initial stem cell transplant. Cells will be T-cell depleted (TCD) by performing a CD34 selection using the CliniMACS device (Miltenyi Biotec) in order to prevent development of new or exacerbation of existing graft versus host disease (GVHD), as avoidance of GVHD in nonmalignant diseases is desirable. There is sufficient data showing that mixed donor chimerism is adequate for reverting disease phenotype in certain primary immunodeficiencies. Observations from Europe and CCHMC show that donor chimerism might be boosted by CD34+ stem cell infusion alone without any specific preparative regimen. This therapy is likely to be associated with low toxicity due to the absence of a preparative regimen and lack of exposure to fresh donor cells capable of initiating GVHD, and offers potential significant benefit.

Inclusion Criteria:

To be eligible for this protocol, patients must have the following:

1. Primary immunodeficiency (e.g. SCID, Wiskott-Aldrich and/or other more rare conditions and other bone marrow failure syndromes) with prior allogeneic stem cell transplant.

2. Waning donor chimerism or immune function that is inadequate to correct their disease or clinical condition, for which primary transplant was given, as determined by their attending physician.

3. Available primary donor.

4. Must not have other organ dysfunction deemed by the attending physician to preclude this procedure.

5. Age < 35 years at time of transplant

6. One of the following must be true:

   • Patients must have evidence of persistent or recurrent immunodeficiency or thrombocytopenia.

-OR-

• Primary immunodeficiency disease with known potential to progress to malignant condition if untreated.

-OR-

• Debilitating secondary disease known to be a consequence of inadequate immune response to known agent or pathogen, uncontrollable by other available medical therapies (e.g. third patient described on page 5).

Exclusion Criteria:

1. Absence of an available original donor
2. Failure to sign consent form, or inability to undergo informed consent process
3. Pregnant or lactating female
4. Uncontrolled GVHD

All AEs were collected for 30 days post stem cell infusion. Protocol-defined AEs related to study treatment were followed for three years.