Morphologic effects of mitoxantrone and a related anthracenedione on lymphoid tissues

A single non-toxic dose of mitoxantrone or a related anthraquinone derivative caused extensive destruction of splenic marginal zone cells in rats and mice. This was followed by phagocytosis of cell debris and long-lasting atrophy. Germinal centers of splenic follicles were also affected. Small doses gave a cumulative effect and tolerance did not develop. Regional draining (but not distant) lymph nodes also had lymphocytic necrosis. The localization of the lymphocytolysis in the spleen may be related to the open circulation of blood in the marginal zone, and to the distribution of B-lymphocytes or B-lymphocyte subsets.