title: Immune response to green fluorescent protein: implications for gene therapy.
abstract: Green fluorescent protein (GFP) is a widely used intracellular reporter molecule to assess gene transfer and expression. A potential use for GFP is as a co-expressed marker, to select and enrich gene-modified cells by flow cytometry. Processed peptides derived from GFP and presented by the major histocompatibility complex on the cell surface could potentially induce T cell immune responses against GFP+ cells. Thus, clinical application of GFP is premature, since in vivo studies on its immunogenicity are lacking. Therefore, we investigated immune responses against EGFP (enhanced-GFP) in two transplantable murine models: the BALB/c (H-2d) BM185 pre-B leukemia and the C57BL/6 (H-2b) EL-4 T cell lymphoma. BM185 and EL-4 cell lines modified to express high levels of EGFP showed drastic reduction of disease development when transplanted into immunocompetent mice. BM185/ EGFP did lead to rapid development of disease in immunodeficient Nu/Nu mice. Mice surviving BM185/EGFP leukemia challenge developed high cytotoxic T lymphocyte (CTL) responses against EGFP-expressing cells. Furthermore, immune stimulation against BM185/EGFP cells could also be induced by immunization with EGFP+ transduced dendritic cells. The effects of the co-expression of EGFP and immunomodulators (CD80 plus GM-CSF) were also investigated as an irradiated leukemia vaccine. EGFP co-expression by the vaccine did not interfere with the development of CTLs against the parental leukemia or with the anti-leukemia response in vivo. These results indicate that the immune response against EGFP may interfere with its applicability in gene insertion/replacement strategies but could potentially be employed for leukemia cell vaccines.
authors.affiliation: Division of Research Immunology/Bone Marrow Transplantation, Childrens Hospital Los Angeles, CA 90027, USA.
authors.forename: R
authors.initials: R
authors.lastname: Stripecke
authors.forename: M
authors.initials: M
authors.lastname: Carmen Villacres
authors.forename: D
authors.initials: D
authors.lastname: Skelton
authors.forename: N
authors.initials: N
authors.lastname: Satake
authors.forename: S
authors.initials: S
authors.lastname: Halene
authors.forename: D
authors.initials: D
authors.lastname: Kohn
mesh_terms: D000818:Animals; D018122:B7-1 Antigen / Q000276:immunology; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology; D049452:Green Fluorescent Proteins; D007942:Leukemia, Experimental / Q000276:immunology* / Q000628:therapy; D008164:Luminescent Proteins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D019444:Vaccines, DNA
chemical_list: D018122:B7-1 Antigen; D008164:Luminescent Proteins; D019444:Vaccines, DNA; D049452:Green Fluorescent Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor