Interaction in culture between mouse ascites mammary carcinoma (MM2) cells and lymphoid cells of isologous mice.

MM2 cells, ascitic tumor originated from spontaneous mammary carcinoma of C3H/He mouse, were mix-cultured with lymphoid cells of thymus or mesenteric lymph nodes from isologous animals of the same sex. The interaction in culture between these cells was examined by time-lapse cinemicrography. In single culture, thymocytes, mesenteric lymph node lymphocytes and MM2 cells were kept for 7 days with little change in cell population. Lymphocytes of both sources showed a marked decrease in cell number when cultured together with MM2 cells, being evidently phagocytosed by MM2 cells. Lymphocytes from MM2-bearing mice or mice sensitized with deoxycholate-extracted MM2 antigen were also all phagocytosed. MM2 cells exhibited no sign of damage or degeneration due to the phagocytosis. Thymocytes were not phagocytosed by histiocytes obtained from ascitic fluid 3 days after i.p. injection of 5% starch suspension. Phagocytosis of erythrocytes or lymphoid cells from spleen by MM2 cells was not detected.