Effector and enhancing lymphoid cells in plasmacytoma-bearing mice. II. Dynamic changes during tumor progression

The Winn assay was used for the study of effector (tumor-inhibiting) and enhancing (tumor-promoting) lymphoid cells in BALB/c mice bearing MOPC-104E plasmacytomas. Kinetic studies with thymus, lymphnode, spleen and bone-marrow cells revealed that spleen, lymph node and to a lesser extent bone-marrow cells from 7- and 10-day tumor-bearers inhibited MOPC-104E growth, while at day 13 all three cell populations enhanced tumor growth. However, at day 16 strong tumor inhibition was observed again by spleen cells and to a lesser extent by lymph-node cells and thymocytes. Peritoneal cells from normal and tumor-bearing (7 and 10 days) animals enhanced tumor growth significantly. Separation of spleen cells on nylon wool columns showed that at 10 days the effector cells were T lymphocytes, but at a later stage (35 days) a different effector mechanism was present in the spleen. Treatment of MOPC-104E recipients with carrageenan or silica had little influence on tumor growth, but marked tumor inhibition occurred after lethal irradiation and bone-marrow reconstitution. This latter observation, together with the finding that bone-marrow, lymph node and peritoneal cells from normal donors enhanced tumor growth in several experiments, suggests that this plasmacytoma, like hormone-dependent tumors, requires lymphocyte-derived growth factors.