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Updated: Jun 14, 2025
Expanding Cytotoxic T Lymphocytes from Umbilical Cord Blood that Target Cytomegalovirus, Epstein-Barr Virus, and Adenovirus
Published on: May 7, 2012
Unrelated cord blood transplantation using minimal-intensity conditioning in a 1.5-month-old infant with X-linked
Shio Takeuchi1, Tomonari Shigemura2, Shohei Shigeto3
1Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan.
Insights
Hematopoietic stem cell transplantation (HSCT) with reduced intensity conditioning effectively restored B-cell function in an infant with X-linked severe combined immunodeficiency (X-SCID). This approach enabled successful immune reconstitution and normal development without significant toxicity.
Area of Science:
- Immunology
- Pediatric Hematology
- Transplantation Medicine
Background:
- Severe combined immunodeficiency (SCID) is a group of genetic disorders characterized by profound deficiencies in T and B lymphocyte functions.
- Hematopoietic stem cell transplantation (HSCT) is the primary treatment for SCID, ideally performed early in life.
- Standard HSCT protocols often require intensive conditioning regimens, which can lead to significant toxicity and complications, particularly in very young infants.
Observation:
- An infant diagnosed with X-linked SCID (X-SCID) presented with cytomegalovirus (CMV) infection shortly after birth.
- The infant underwent unrelated cord blood transplantation (CBT) at 1.5 months of age, utilizing a reduced-intensity conditioning regimen (fludarabine and melphalan).
Findings:
- The CBT procedure was well-tolerated, with the CMV infection effectively managed by antiviral therapy.
- Immunoglobulin (Ig) replacement therapy was discontinued at 6 months post-transplant due to the development of sufficient CD27+ memory B cells and successful post-vaccine immunity.
- The patient exhibited normal growth and psychomotor development at 5 years and 7 months post-transplant, indicating no adverse effects from the chemotherapy regimen.
Implications:
- Reduced-intensity conditioning regimens for CBT can be a safe and effective strategy for treating X-SCID in young infants.
- Successful B-cell reconstitution allows for the cessation of Ig replacement therapy and the acquisition of protective immunity.
- This approach minimizes transplant-related toxicity while achieving long-term immune reconstitution, offering a promising therapeutic option for SCID.
Background:
Severe combined immunodeficiency (SCID) is a heterogenous disorder with profound deficiency of T/B-cell functions. The best SCID therapy requires hematopoietic stem cell transplantation (HSCT) early in life. HSCT with conditioning is necessary to achieve a long-term reconstitution of B-cell functions. However, conditioning may aggravate pre-existing infection and cause transplant-related toxicity, especially in very young infants. Hence, the intensity of conditioning should be reduced to allow the reconstitution of immunity including B cells to the extent that prevents transplant-related toxicity and delayed complications.
Methods:
An infant with a family history of X-linked SCID (X-SCID) was diagnosed with X-SCID disorder soon after birth. The infant exhibited cytomegalovirus (CMV) infection despite being strictly isolated. At 1.5 months of age, we performed an unrelated cord blood transplantation (CBT) with a less intensity conditioning regimen: fludarabine (125 mg/m2) + melphalan (80 mg/m2). We evaluated the efficacy of reconstitution by assessing B-cell function and growth and psychomotor development at 5 years and 7 months after CBT.
Results:
The clinical course after CBT was uneventful after CBT. The CMV infection was fully controlled by ganciclovir or foscavir therapy, which was discontinued at day 55 after CBT. Furthermore, immunoglobulin (Ig) replacement therapy was also discontinued at 6 months after CBT. A sufficient proportion of CD27+ memory B cells was developed, which was essential for an effective vaccination and prevention of infections. While the B-cell chimerism became recipient-dominant, the Ig replacement therapy was substituted by very successful post-vaccine immunity acquisition after CBT. The analysis of the general developmental parameters showed that chemotherapy did not cause any delay in growth and psychomotor development.
Conclusions:
The CBT therapy with this conditioning regimen was well tolerated and induced an effective reconstitution of B-cell functions in an X-SCID infant under the 3 months of age.
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