Cell cycle and morphological changes during growth and differentiation of a rat basophilic leukemia cell line

Cells of the rat basophilic leukemia cell line RBL-1 differentiated maximally when permitted to achieve growth arrest in a high-density stationary phase, in which the cell number is constant, and the cells are arrested in a G phase of the cycle. Features of differentiation are the accumulation of large basophilic granules and increases in membrane receptors for immunoglobulin E. However, changes in histamine content did not parallel granule development or changes in immunoglobulin receptor concentration. During rapid "forced exponential" growth, the cell number doubles every 8 hr, 50% of the cells are in S phase, and differentiation is minimal.