Immunization with a Recombinant Adenovirus Encoding a Lymphoma Idiotype: Induction of Tumor-Protective Immunity and Identification of an Idiotype-Specific T Cell Epitope

Abstract

The Ig Id of a B cell lymphoma is a tumor-specific Ag, although as a self-Ag it is likely to be a weak immunogen. Provision of a foreign gene may enhance the immunogenicity of the idiotype. Viral vectors allow highly efficient transfer of genetic material and are themselves innately immunogenic. We have investigated the ability of recombinant adenoviral vectors, encoding the idiotypic gene with or without fusion to the human Fc region, to produce anti-idiotypic Ab- and T cell-mediated responses in a syngeneic BALB/c A20 murine lymphoma model. The idiotypic VH and VL sequences were assembled as a single chain variable fragment (scFv) and adenoviral vectors encoding the A20 scFv (Ad.A20) and A20 scFv linked to the Fc fragment of human IgG1 (Ad.A20hFc) were constructed. A single immunization of BALB/c mice with Ad.A20hFc but not Ad.A20 induced a specific anti-idiotypic Ab response. T cell lines generated from mice vaccinated with either vector displayed specific cytotoxicity, proliferation, and IFN-γ release against a syngeneic dendritic cell line transduced using a retroviral vector to express the A20 scFv idiotype (XS52.A1.A20). Importantly, both T cell lines lysed the A20 lymphoma cells. An immunodominant H-2Kd-restricted CD8+ T cell peptide, DYWGQGTEL (A20[106–114]), was identified as a naturally occurring A20 scFv epitope. A single immunization with Ad.A20hFc but not Ad.A20 provided protection in >40% of animals challenged with a lethal dose of the A20 tumor line and was more effective, in this model, than a previously optimized plasmid vaccine.

Use of adenoviruses encoding CD40L or IL‐2 against B cell lymphoma

“…11 Treatment with the A20-Ad-mCD40L delayed significantly the development of tumors compared to the A20-Ad-mIL-2, A20-AdLacZ and non-infected A20 treated groups (Fig. 6).…”

“…We have recently investigated the ability of recombinant adenovirus encoding a lymphoma (A20) Id gene fused to a human IgG1 Fc helper determinant that can induce an anti-idiotypic immune response capable of protecting syngeneic mice from tumor challenge. 11 The use of idiotype vaccines is limited, however, by the fact that Id is individual lymphomaspecific. Modulation of B cells lymphoma and their use as cellbased vaccines has been investigated by previous studies and the use of lymphoma cells genetically engineered to produce GM-CSF 19 has been successful but failed in the generation of any humoral immunity.…”

“…XS52-A20-A1 cell line, an XS52-derived dendritic cell line retrovirally transduced to express the A20 scFv, was generated in our laboratory. 11 This cell line was grown in the same medium as XS52.…”

“…8 The Id is a weakly immunogenic self-antigen and immuno-modulation by fusion to more immunogenic antigens has been shown to enhance its immunogenicity. This can be achieved by fusion to the granulocyte macrophage colony stimulating factor (GM-CSF), 9 the MCP-3 chemokine, 10 the constant region of a foreign immunoglobulin (Ig) [11][12][13] or to the non-toxic C fragment (FrC) of tetanus toxin. 14 All these methods provide T cell help to break tolerance against the Id antigen.…”

Professor Tom Connors and the development of novel cancer therapies by the Phase I/II Clinical Trials Committee of Cancer Research UK

“…Looking to the future, viral DNA delivery, as opposed to naked plasmid gene administration, may be more efficient (Armstrong et al, 2002), either used alone or in combination with dendritic cells. Recent studies with protein-loaded dendritic cells have demonstrated clinical activity (Timmerman et al, 2002), and dendritic cells have the advantage of efficient antigen uptake and presentation, as well as the expression of the full range of accessory molecules required for an efficient immunodynamic effect.…”