In vivo study of the GC90/IRIV vaccine for immune response and autoimmunity into a novel humanised transgenic mouse

Abstract

Parathyroid hormone-related protein (PTH-rP), a secreted protein produced by prostate carcinoma and other epithelial cancers, is considered a key agent for the development of bone metastases. We investigated the construct GC90/IRIV, composed of immunopotentiating reconstituted influenza virosomes (IRIV) containing PTH-rP gene plasmids (GC90), as a potential tool for human anticancer immunotherapy into humanised mice transgenic for HLA-A(*)02.01, the human-beta2 microglobulin, and the human CD8alpha molecule. Intranasal administration of GC90/IRIV resulted in the induction of a PTH-rP-specific multiepitope cytotoxic T-cell (CTL) response. Cytotoxic T cells derived from vaccinated mice were capable of lysing in vitro syngenic murine PTH-rP transfectants and human HLA-A((*))02.01(+)/PTH-rP(+) prostate carcinoma LNCaP cells as well. The immune response capacity and the absence of any sign of toxicity and/or autoimmunity in vivo suggest the GC90/IRIV vaccine as a valid tool for active specific immunotherapy of human cancers and metastases overexpressing PTH-rP.

Figure 1

Parathyroid hormone-related protein-specific cytotoxic activity of spleen cells derived from triple transgenic mice immunised with GC90/IRIV +/− PTH-rP peptides. Cultured spleen cells derived from different groups of mice respectively immunised with GC90/IRIV (-•-), GC90/IRIV+PTR-1 (-▪-), GC90/IRIV+PTR-2 (-▴-), GC90/IRIV+PTR-3 (-○-), GC90/IRIV+PTR-4 (-□-), and empty IRIV group (–▵–). Parathyroid hormone-related protein-specific cytotoxic activity of mouse spleens pooled from different mouse groups was tested against EL4/HHD target cells transfected with the PTH-rP gene (A) in fresh medium or in the presence of anti-A2.69 mAb (B).

Figure 2

Parathyroid hormone-related protein-specific cytotoxic activity of spleen cells derived from triple transgenic mice immunised with GC90/IRIV +/− PTH-rP peptides in vitro against HLA-A(^*)02.01⁺ PTH-rP⁺ LNCaP cells. Cultured spleen cells were derived from different groups of transgenic mice respectively immunised with GC90/IRIV (-•-), GC90/IRIV+PTR-1 (-▪-), GC90/IRIV+PTR-2 (-▴-), GC90/IRIV+PTR-3 (-○-), GC90/IRIV+PTR-4 (-□-), and empty IRIV group (–▵–). Parathyroid hormone-related protein-specific cytotoxic activity of mouse spleens pooled from different mouse groups was tested against LNCaP target cells in fresh medium (A) or in the presence of anti-A2.69 mAb (B).