Reid, I

Abstract Tumor-infiltrating lymphocytes (TIL) were obtained from a mouse melanoma cell line (CL 62) transfected with the gene for the human melanoma Ag p97. TIL were cultured with anti-CD3 antibody and IL-2 for up to 38 days. Flow cytometry identified these TIL as Thy-1.2 + ve/CD4-ve/CD8 + ve cells. A heteroconjugated antibody 500A2 x 96.5, specific for both the CD3 Ag on TIL and the p97 Ag on CL 62 melanoma cells, was prepared using N-succinimidyl-3-(2-pyridyldithio)-propionate as a linking agent. TIL alone demonstrated low levels of cytotoxicity against autologous CL 62 tumor and also against the parental K1735 tumor and an allogeneic murine melanoma (B16). The addition of 500A2 x 96.5 heteroconjugated antibody enhanced TIL-mediated lysis of CL 62 tumor, but not of the K1735 or B16 tumors. This enhanced cytotoxicity was elicited at E:T ratios as low as 0.4:1, and in TIL cultured for 7 to 38 days. These results suggest that hetero-conjugated antibody may enhance the anti-tumor effect of TIL in vivo.

Abstract Covalent linkage of an antitumour antibody specific for a tumour cell surface antigen to an antilymphocyte antibody specific for the T lymphocyte receptor complex produces a heteroconjugated antibody that can activate and redirect cytotoxic T lymphocytes to lyse tumour cells. The ability of an antilymphocyte-antitumour heteroconjugate (500A2 × 96.5) to direct the lysis of murine melanoma cells by cultured murine lymphocytes was tested in vitro using a 4-h chromium release assay and in vivo with a tumour neutralization assay. In vitro, the addition of heteroconjugated antibody significantly increased tumour lysis by murine C3H/HeN lymphocytes (median specific lysis 82.7 per cent with lymphocytes plus heteroconjugate versus 9.5 per cent for lymphocytes alone, P < 0.001). In vivo, treatment with heteroconjugated antibody plus lymphocytes significantly reduced the development of pulmonary metastases after intravenous tumour administration (median number of pulmonary metastases 28.5 for combined treatment versus 250 for heteroconjugate or lymphocytes alone, P < 0.001).