Cytotoxic TILs infiltrate tumors expressing higher or lower levels of the gp33 antigen in a similar manner. (A) In both the gp33 tumor model and the SIY tumor model, the percentage of T cells in tumors expressing either higher or lower levels of antigen was analyzed at 1, 2, 4, or 6 d after T cell transfer. (B) P14 T cells infiltrated gp33-Hi and gp33-Lo tumors 6 d after T cell transfer (20 d after tumor growth). The numbers in the upper-right quadrant are the percentages of V-alpha2+ CD8+ cells in the bulk tumor cells. (C) Six days after T cell transfer, Thy1.1+ cells isolated from the indicated tumors were stimulated with the gp33 peptide for 6 h and then stained with anti-CD8 and anti-IFN-gamma antibodies. The numbers in the upper-right and lower-right quadrants are the percentages of IFN-gamma+ CD8+ T and IFN-gamma- CD8+ cells, respectively. (D) Thy1.1+ cells isolated from the indicated tumors were tested in a ⁵¹Cr release assay using the targets indicated.