Electron Microscopic Observations of the Interaction of Macrophages and Lymphocytes in a Virus-Induced Murine Lymphoma

A tissue culture line of the Rauscher virus induced a murine lymphoma which was maintained by serial passage. Histologically, this tumor consisted of a sheet of immature lymphoid cells interspersed by large histiocytes (the "starry sky" pattern). Typical mouse leukemia virus particles budded from the plasma membranes of the lymphoid cells. Virus particles were seen in the starry sky areas which were formed by large histiocytes and cytoplasmolysis and nucleoly-sis of the lymphoid cells. Debris of lymphoid cells containing virus particles was phagocytized by macrophages. It is suggested that this histological pattern characterizes lymphomas with his-toincompatibility between host and malignant cells.