The anti-tumor immune responses induced by a fusion protein of ovarian carcinoma anti-idiotypic antibody 6B11ScFv and murine GM-CSF in BALB/c mice

Abstract

Ovarian carcinoma anti-idiotypic antibody 6B11 was murine derived; we previously have cloned 6B11 single-chain Fv antibody (6B11ScFv) and constructed the 6B11ScFv/human granulocyte-macrophage colony stimulating factor (GM-CSF) fusion protein (designated as 6B11GM) to enhance the immunogenecity of the single-chain Ab(2). Because of the difference in species specificity between human GM-CSF and murine GM-CSF, there is no immune competent animal model on which the effect and metabolism of 6B11GM as a vaccine could be observed. In this study, 6B11mGM fusion gene was constructed by the fusing murine GM-CSF cDNA gene with 6B11ScFv. The fusion gene was cloned and expressed. The product of this gene is a fusion protein. It could specifically interact with the primary anti-ovarian carcinoma monoclonal antibody (COC166-9) and rat anti-mouse GM-CSF monoclonal antibody, respectively, and stimulate the growth of NFS-60 cells (a murine GM-CSF-dependent cell line). The specific anti-tumor immune response could be induced in BALB/c mice after immunized with anti-idiotypic fusion protein instead of ovarian carcinoma antigen without carrier proteins and adjuvant. Ab(3) could be detected in the sera of immunized mice with 6B11mGM by enzyme-linked immunoadsorbent assay test. Moreover, the fusion protein stimulated proliferation of CD4+ T cell from the spleen of BALB/c mice and proliferation of CD8+ T cell to a lesser degree. Therefore, 6B11mGM probably induces both humoral and cellular immunity against ovarian carcinoma in vivo.

Efficacy of recombinant adenovirus expressing a fusion gene from GM-CSF and Epstein-Barr virus LMP2A in a mouse tumor model

“…Intratumoral injection of recombinant adenovirus expressing the GM-CSF gene has been shown to effectively induce the human anti-tumor immune response. 8 The LMP2A protein effectively triggers the CTL response, and many researchers have attempted to induce LMP2A CTLs for the treatment of EBV-positive tumors. The LMP2A gene encodes the EBV latent membrane protein, which stimulates the production of antibodies.…”

“…Other types of tumor cells that stably express one of the few conservative EBV antigens have been demonstrated to activate T cell epitopes and to be mediated by cytotoxic T cells. 6 Redchenko and Rickinson 7 used the LMP2A epitope peptide to load DCs and demonstrated the induction of strong, specific CTL immune responses, indicating that LMP2A is an ideal target antigen for immunotherapy of EBV-associated tumors. Therefore, we hypothesized that if the LMP2A gene is inserted into an expression vector, alone or in combination with another gene, the cells may express this target antigen and induce the production of specific cellular or humoral immunity, preventing EBV infection and killing EBV-positive tumor cells.…”

“…The transfer of GM-CSF into tumor cells could greatly enhance their immunogenicity and effectively improve the human anti-tumor response. 8 GM-CSF not only promotes DC proliferation, differentiation, and viability but also plays an important regulatory role in DC distribution in vivo and in antigen presentation. The transfer of GM-CSF into tumor cells could greatly enhance their immunogenicity, improving the organism-specific anti-tumor response.…”

“…GM-CSF recombinant adenovirus also effectively induces anti-tumor immunity; intratumoral injection of a GM-CSF expression vector cotransformation could enhance the body's anti-tumor response. 8,9 GM-CSF expression activates or attracts antigen-presenting cells to the tumor site, and it is involved in the anti-tumor immune response.…”

Prognostic value and characterization of the ovarian cancer-specific antigen CA166-9

“…The sera tested by 6B11 presented 67.3% positivity of ovarian epithelial carcinoma, much higher than that of the benign ovarian tumor or uterine tumors (11). Besides, the recombinant single-chain variable fragment (ScFv) of 6B11 has demonstrated killing effects against ovarian cancer cells in vitro and in vivo (12)(13)(14). Moreover, a study on identification of antigen-specific T cell eptitopes in 6B11 found that the light chain CDR3 peptide and heavy chain CDR3 peptide are the MHC class I and class II epitopes of 6B11, respectively.…”