Activated T cells (ATC) that have been coated with bispecific antibodies (BiAb), with potential antineoplastic and immunomodulating activities. In vitro, T cells are activated through exposure to the anti-CD3 murine monoclonal antibody OKT3 and interleukin 2 for 14 days and then armed with anti-CD3 × anti-Her2 bispecific antibody (Her2Bi). Upon administration, HER2Bi-armed activated T cells attach to CD3-expressing T cells and HER2/neu-expressing tumor cells, selectively cross-linking T cells and tumor cells; this may result in the recruitment and activation of cytotoxic T lymphocytes (CTLs), CTL perforin-mediated tumor cell cytolysis, and the secretion of antitumor cytokines and chemokines.