Antitumor activity of antibody against cytotoxic T lymphocyte epitope peptide of lymphocyte-specific protein tyrosine kinase.

Although humoral responses against CTL epitope peptides from lymphocyte-specific protein tyrosine kinase (Lck) antigen have been observed in the majority of healthy donors and cancer patients, the biological activity of the antibody has not been determined. We investigated the biological activity of mAb against CTL epitope peptide of Lck antigen at positions 486-494 (anti-Lck-486 mAb). This mAb induced dendritic cell maturation from murine bone marrow cells by the immune complex form in vitro, and inhibited tumor growth in association with a suppression of tumor-infiltrating T cells, including T regulatory cells in a murine model using female BALB/cCrlCrlj mice (H-2K ). More potent tumor inhibition was observed when this mAb was given prior to peptide vaccination. These results may help to unveil the biological activity of anti-Lck peptide antibodies against CTL epitope peptides.