Induction of T cell tolerance to a protein expressed in the cytoplasm through retroviral-mediated gene transfer.
BACKGROUND
Host immune responses to foreign gene products have been shown to lead to the elimination of genetically modified cells, and are a major barrier to successful therapeutic gene therapy. We have shown that immunological tolerance to retrovirally transduced cell surface proteins can be induced by expressing the gene encoding these products in bone marrow derived cells. Here, we investigate if expression of foreign gene products in bone marrow derived cells can be used to induce tolerance to cytoplasmic proteins.


METHODS
Balb/c mice were reconstituted with syngeneic bone marrow cells transduced with retrovirus carrying the gene encoding enhanced green fluorescent protein (eGFP), or mock-transduced bone marrow cells. After reconstitution, mice were immunized with cells expressing eGFP, and T cells were tested for the ability to kill eGFP-expressing targets in in vitro cytotoxic T lymphocyte (CTL) assays.


RESULTS
T cells from Balb/c mice reconstituted with mock-transduced bone marrow were able to kill target cells expressing eGFP. In contrast, T cells from mice reconstituted with eGFP-transduced bone marrow were unable to kill targets expressing eGFP. In addition, we observed that T cell responses to eGFP in C57BL/6 mice were minimal even under highly immunogenic conditions.


CONCLUSIONS
These data suggest that expression of foreign gene products in bone marrow derived cells is capable of inducing T cell tolerance to proteins expressed exclusively in the cytoplasm.
Transplantation Biology Research Center, Massachusetts General Hospital and Harvard Medical School, MGH-East, Building 149, 13th St., Boston 02129, USA.
Chaorui
C
Tian
Jessamyn
J
Bagley
Joel
J
Kaye
John
J
Iacomini
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology; D016026:Bone Marrow Transplantation; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods; D049452:Green Fluorescent Proteins; D007108:Immune Tolerance; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics*; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism
D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins