Myeloperoxidase and crystalline bodies in the granules of DMBA-induced rat chloroma cells.

Chloroma (chloroleukemia) was induced in a splenectomized rat by repeatedly administering dimethylbenz(a)anthracene (DMBA) and was serially transplanted thereafter. Composed of immature myeloid cells, the tumor imparted a green discoloration to the tissues that it infiltrated extensively. Chloroma cells fluoresced red in ultraviolet light, produced a characteristic curve in spectrophotometry, and contained large amounts of myeloperoxidase. They included numerous intracytoplasmic granules of both types A and B, which contained occasional crystalline bars. Permanent lines of chloroma cells were established in tissue culture. These cells, while maintaining their initial morphology, ceased producing myeloperoxidase and subsequently induced white tumors when they were isotransplanted.