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Expression of human CD18 in murine granulocytes and improved efficiency for infection of deficient human lymphoblasts
R W Wilson1, T Yorifuji, I Lorenzo
1Institute for Molecular Genetics, Baylor College of Medicine, Houston, TX 77030.
Abstract:
The CD18 gene encodes the beta 2-subunit of leukocyte integrins, and mutations in this gene cause extreme host susceptibility to bacterial and fungal infection. Because expression of CD18 is restricted to bone marrow-derived cells, this disorder is considered an excellent candidate for somatic gene therapy utilizing ex vivo infection of bone marrow stem cells. We have constructed a retroviral vector expressing CD18 with the Moloney murine leukemia virus (Mo-MLV) long terminal repeat (LTR) as the promoter, and high-titer ecotropic and amphotropic producer cell lines were isolated using the GP+E-86 and GP+envAM12 safe packaging cell lines. Infection of CD18-deficient lymphoblasts resulted both in expression of immunodetectable CD18 at 35-40% of normal levels on 55-60% of cells and in functional restoration of CD18-dependent aggregation. All of 16 mice transplanted with syngeneic bone marrow infected with the CD18 retrovirus expressed human CD18 on 17-36% of granulocytes at 2 weeks after transplantation, and expression was appropriately up-regulated in response to stimulation with zymosan-activated serum. This recombinant retrovirus should prove useful for further studies of somatic gene therapy for CD18 deficiency.
Insights
Somatic gene therapy shows promise for CD18 deficiency, a condition causing severe infections. Researchers developed a retroviral vector to deliver the CD18 gene, restoring immune cell function in preclinical models.
Area of Science:
- Immunology
- Molecular Biology
- Gene Therapy
Background:
- Mutations in the CD18 gene lead to severe susceptibility to bacterial and fungal infections.
- CD18 is crucial for leukocyte integrin function.
- Somatic gene therapy targeting bone marrow stem cells is a potential treatment strategy.
Purpose of the Study:
- To develop and evaluate a retroviral vector for CD18 gene delivery.
- To assess the efficacy of ex vivo gene therapy for CD18 deficiency.
Main Methods:
- Construction of a retroviral vector encoding CD18 using Mo-MLV LTR.
- Isolation of high-titer producer cell lines.
- Infection of CD18-deficient lymphoblasts and bone marrow stem cells.
- Transplantation of gene-modified bone marrow into mice.
Main Results:
- Infection of lymphoblasts restored CD18 expression and function.
- Transplanted mice showed sustained CD18 expression in granulocytes.
- Expression levels were responsive to inflammatory stimuli.
Conclusions:
- The developed retroviral vector effectively delivers the CD18 gene.
- This approach shows potential for treating CD18 deficiency through somatic gene therapy.
- Further studies are warranted to advance this therapeutic strategy.