The phenotypes of variant clones of Friend mouse erythroleukemic cells resistant to dimethyl sulfoxide.

The cloning efficiency of Friend erythroleukemic mouse cells is reduced by approximately 50% at every generation when the cells are continuously grown in the presence of 2% dimethyl sulfoxide (DMSO). Clones of murine erythroleukemic cells, resistant to the effect of the drug, have been selected from a nonmutagenized, hemoglobin (Hb)-inducible clone 745. The variant cells are present in the population with a frequency of 3 X 10(-5) cells. Twelve clones, characterized by different growth rates, have been examined in more detail. All the clones can grow in the continuous presence of 2% DMSO, are noninducible or poorly inducible by the drug, and consist of a homogeneous proerythroblastic cell population and a low number of Hb-synthesizing cells, except for clone R22S in which about 30% of the cells synthesize Hb. All but one (R2102) of the noninducible clones can be induced to synthesize Hb to various degrees by treatment with 1 mM butyric acid for 4 days. One clone (R1Z) forms colonies at a much higher efficiency in 2% DMSO than in nonselective plates, suggesting that it is conditional for DMSO. These and other resistant clones could be useful for the study of the mechanisms of induction of terminal differentiation.