Interaction in culture between mouse ascites hepatoma (MH-134) cells and lymphoid cells of isologous mice.

Thymocytes or lymphocytes of mesenteric lymph nodes were obtained from mice bearing subcutaneously mouse ascites hepatoma MH-134 for 5 to 40 days. These lymphoid cells were added into the cultures of MH-134 cells. Morphological changes of cells in the mixed cultures were observed by time-lapse cinemicrography for the period of 4 weeks. Lymphoid cells were phagocytosed by MH-134 cells, and, in most cases, the tumor cells did not undergo any damage due to the phagocytosis. The exceptional cases were as follows: When MH-134 cells were mixed with thymocytes from mice bearing MH-134 tumor for 5 days, MH-134 cells phagocytosed thymocytes but some of them died later. In the mixed cultures of MH-134 cells and thymocytes or mesenteric lymph node lymphocytes from mice bearing MH-134 for 14 or 15 days, MH-134 cells phagocytosed lymphoid cells but died later by the burst of cytoplasm. By the burst many lymphoid cells phagocytosed appeared from the broken cytoplasm of MH-134 cells and, in some cases, the lymphoid cells looked to be alive. These findings suggest the possibility that lymphoid cells attack tumor cells not only from the cell surface but also from the inside being phagocytosed by tumor cells.