Electron microscopic study of human leukemic cells in tissue culture

Cell lines originating from three cases of acute human leukemia have been studied under the electron microscope. The fine structure of the cultured cells has been compared to that of the patients' circulating leukocytes and progressive dedifferentiation has been described. After several months in culture, most of the cells resemble large primitive blasts or stem cells. One line, however, showed a transient wave of differentiation with the appearance of eosinophilic metamyelocytes. Problems of myeloid-cell nomenclature have been raised in the light of the study of the same material by conventional hematologic methods. Virus particles were not observed in the patients' circulating leukocytes, or in the cell cultures derived from them, despite repeated efforts to induce some degree of cell degeneration.