Tissue culture cells from various leukemic bone marrow were stained with acridine orange and studied with the fluorescence microscope from the beginning of staining to the death of stained cells. Following was the results obtained.
1. By addition of acridine orange solution into the tissue culture medium, the nuclei of mature leukocytes from normal bone marrow revealed green fluorescence, and their cytoplasmic granules reddish orange. In degenerated leukocytes, however, nuclei and nucleoli displayed orange fluorescence immediately after additioning the dye, and then, loosing their fluorescence, they became green. Meanwhile, red fluorescence of granules was gradually discolored and became invisible without changing the color.
2. The nuclei of mature leukocytes in acute leukemias, especially neutrophils in acute myelogenous, lymphocytes in acute lymphocytic, basophils in acute basophilic, and monocytes in monocytic leukemia, were stained with a more reddish tinge and their granules were discolored in the earlier stage of the tissue culture than those in normal bone marrow.
3. The red fluorescence of the nucleoli within the green nuclei was characteristic of leukemic cells in monocytic and acute myelogenous leukemias. However, the nucleoli became gradually vague, since, as time elapses, the nuclei changed into orange in color.
4. In cultured cells of chronic leukemias, no characteristic fluorescence was observed as compared with those of normal bone marrow.
5. In the present study, it was conceivable that cellular functions of leukemic bone marrow cells was damaged in acute leukemias, and not damaged in chronic leukemias by the acridine orange staining.