[In vivo study of antitumor immune responses induced by anti-idiotypic minibody vaccine of ovarian cancer].

Background & Objective: 6B11 anti-idiotypic minibody can be constructed by fusion of anti-idiotypic single chain antibody (6B11scFv) to human IgG(1) hinge and CH3, which can simulate the function of ovarian carcinoma antigen. It has immune activity of both 6B11 and human immunoglobulin IgG(1) Fc. This study was designed to evaluate whether anti-tumor immune response can be induced in BALB/c mice immunized with 6B11anti-idiotypic minibody and explore its probability as ovarian cancer vaccine.

Methods: BALB/c mice were immunized repeatedly by 6B11 anti-idiotypic minibody. Competition inhibition test, indirect ELISA test, and immune flow cytometry were used for analyzing the serum characterization of anti-anti-idiotypic antibody (Ab3) and the changes of T lymphocyte phenotype of spleen.

Results: The specific antitumor immune response could be induced in BALB/c mice after immunized with anti-idiotypic minibody without carrier proteins and adjuvant. The Ab3 maintained at a high level till 30 day after the last immunization. It stimulated proliferation of CD4+ T cells and CD8+ T cells from the spleen of BALB/c mice on 4th day, 14th day, 24th day, and 30th day after the last immunity respectively.

Conclusions: 6B11 anti-idiotypic minibody can induce both humoral and cellular immunity against ovarian carcinoma in vivo, which provided experimental evidence for clinical use of fusion protein 6B11 minibody as anti-idiotype vaccines against ovarian carcinoma.