Effector and enhancing lymphoid cells in plasmacytoma-bearing mice. I. Methodological studies on the winn assay

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Abstract
Some parameters of the Winn assay for the detection of tumor‐suppressing (“effector”) and tumor‐enhancing lymphoid cells were studied in BALB/c mice. Spleen cells of mice that were preimmunized with mitomycin‐C‐treated MOPC‐104E plasmacytoma cells were inhibitory in this test system for both the MOPC‐104E and the HOPC‐1 plasmacytomas, thus indicating cross‐reactivity. Spleen cells taken from mice 6 days after the surgical removal of 15‐day‐old MOPC‐104E tumors inhibited the growth of lethal doses of MOPC‐104E cells in normal recipients, but no inhibition was observed 2 days after the removal of 18‐day‐old tumors. Spleen cells from mice bearing MOPC‐104E for 13 days enhanced tumor growth. This enhancement was not influenced significantly by the wide dose range (from 105 to 3 × 107) of MOPC‐104E cells used to initiate tumors in the lymphoid cell donors, although a tendency for stronger enhancing potential occurred after low tumor doses. When spleen cells from donors bearing MOPC‐104E for 10 days were injected at the constant tumor‐lymphocyte ratio of 1:30 with increasing numbers of tumor cells (from 5 × 105 to 2 × 106), tumor inhibition occurred at the lowest dose only, while no significant effect was observed at higher tumor cell doses. When a constant dose (5 × 105) of tumor cells was injected with spleen cells from 10‐day tumor‐bearers at tumor/lymphocyte ratios of 1:10, 1:40 and 1:160, a significant tumor inhibition occurred only at the ratio of 1:40. The relevance of the Winn test to the study of immune mechanisms in tumor‐bearing hosts is discussed.