title: Tumor-infiltrating lymphocytes can be activated in situ by using in vivo activants plus F(ab')2 bispecific antibodies.
abstract: In vitro-activated T lymphocytes can be retargeted with anti-CD3 x anti-tumor bispecific antibodies (BsAb) to kill tumor cells in vitro and in vivo. The purpose of the present study was to examine the systemic and intra-tumor effects of in vivo T-cell activation with BsAb, staphylococcal enterotoxin B (SEB), and beta-glucan in combination with BsAb as a retargeting agent. CL-62 melanoma cells were injected subcutaneously into C3H/ HeN mice. Mice were subsequently treated with BsAb alone or with SEB or beta-glucan plus BsAb. Fresh splenocytes, lymph-node cells and tumor-infiltrating lymphocytes (TIL) were tested for their proliferative response using incorporation of 3H-thymidine, and for their ability to lyse CL-62 cells in the presence or absence of BsAb in 4-hr 51Chromium release assays. Toxicity of treatments was assessed in a D-galactosamine model. BsAb, alone or combined with beta-glucan, had essentially no effect on systemic T-cell cytotoxicity, and essentially no effect on systemic proliferation, unless exogenous IL-2 was provided. At the tumor site, BsAb alone, BsAb plus beta-glucan, and SEB plus BsAb all significantly increased BsAb-mediated TIL cytotoxicity. In contrast to the TIL-limited effects of BsAb and of BsAb plus beta-glucan, SEB plus BsAb markedly increased both systemic and intra-tumor T-lymphocyte activation. Toxicity correlated with measures of systemic activation, with limited effects from BsAb alone and from beta-glucan plus BsAb, and with marked lethality from SEB plus BsAb. Overall, these results suggest moderate intra-tumor activation of TIL, but no measurable systemic activation after in vivo treatment with BsAb or beta-glucan plus BsAb. SEB plus BsAb results in complete T-cell activation in both systemic and intra-tumor compartments, but at the expense of increased systemic toxicity. In conclusion, TIL can be activated in situ with different combinations of in vivo activants. In vivo-activated TIL can be retargeted with bispecific antibodies to lyse tumor cells, and may be an alternative to ex vivo T-cell activation and adoptive transfer therapy.
authors: Division of Colon and Rectal Surgery, Mayo Clinic, Rochester, MN, USA.
authors: C
authors: C
authors: Thibault
authors: H
authors: H
authors: Nelson
authors: A I
authors: AI
authors: Chapoval
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000494:pharmacology* / Q000633:toxicity; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic; D004768:Enterotoxins / Q000494:pharmacology / Q000633:toxicity; D005936:Glucans / Q000494:pharmacology; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology* / Q000633:toxicity; D008213:Lymphocyte Activation / Q000187:drug effects*; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008546:Melanoma, Experimental / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D009368:Neoplasm Transplantation; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D018033:Antibodies, Bispecific; D004768:Enterotoxins; D005936:Glucans; D007140:Immunoglobulin Fab Fragments; C031818:enterotoxin B, staphylococcal