Cell-mediated cytotoxicity of tumor infiltrating lymphocytes on rat bladder cancer

Tumor-infiltrating lymphocytes (TIL) were tested for cytotoxicity against autologous tumor cells in a study utilizing a chemically induced cancer of the bladder (transitional cell carcinoma), BC-47, in inbred ACI/N rats. From tumors grown after subcutaneous implantation of BC-47 in the rats TIL were separated by density gradient centrifugation and incubated in plastic dishes for separation of non-adherent from adherent cells. The non-adherent cells were further fractionated into T and B cells by the panning method using anti-rat F(ab')2 antibody. The cell fractions were each added to BC-47 in culture to be assessed for antitumor effect by the crystal violet dye exclusion method and 3H-thymidine incorporation inhibition assay. Peripheral blood mononuclear cells (PBMC) were also tested as described above. TIL expressed significantly higher cytotoxicity against BC-47 with the mean % cytotoxicity of 56.6 +/- 5.6% and 87.5 +/- 7.1% at E/T ratios of 10:1 and 20:1, respectively, as compared to PBMC (9.9 +/- 5.0% at E/T 10:1) (P < 0.001). The adherent cells, B and T cell fractions showed respective % cytotoxicity of 92.4 +/- 2.8%, 57.9 +/- 10.6% and 9.9 +/- 7.8% at an E/T ratio of 10:1. TIL pretreated with IFN or rIL-2 for 24 or 48 hours did not exhibit any noticeably enhanced antitumor activity at an E/T ratio of 5:1. Prevention of direct contact of BC-47 cells and TIL by an interposed Millipore membrane (0.45 microns) resulted in an unequivocal reduction of antitumor effect.(ABSTRACT TRUNCATED AT 250 WORDS)