CHARACTERIZATION OF A MURINE OVARIAN RETICULUM-CELL SARCOMA OF HISTIOCYTIC ORIGIN

Abstract

The M5076 tumor, a transplantable murine reticulum cell sarcoma that arose spontaneously in the ovary of a C57BL/6 mouse was studied. This tumor dispays functional and ultrastructural characteristics indicating that it is of macrophage origin. Cells from the M5076 tumor are phagocytic, form rosettes with sheep red blood cells, mediate antibody-dependent cellular cytotoxicity against 51Cr-labeled red blood cells, and dispay macrophage-like cytotoxicity against syngeneic tumor target cells but do not exhibit any natural killer cell activity. The tumor cells possess lysozyme, nonspecific esterase and phosphatase activities comparable to those seen in rodent macrophages. Ultrastructural examination revealed phagocytic vacuoles and a lack of tight junctions typical of macrophage morphology. Karyotype analysis showed that M5076 tumor cells are hypodiploid with a high percentage (> 80%) of metacentric chromosomes that serve as an excellent marker for identification of these tumor cells.