Differentiation-stimulating factor (D-factor)/leukemia inhibitory factor is a cytokine inducing differentiation of mouse myeloid leukemie M1-T22 cells. The effect of recombinant human D-factor on growth and differentiation of pig kidney LLC-PK1 cells was examined. LLC-PK1 cells did not concentrate α-methylglucoside during their early growth in culture but developed the capacity to concentrate this hexose as they reached confluence and their growth rate decreased. Purified D-factor caused dose-dependent inhibition of the development of this concentrative capacity. It did not affect the growth rate of the cells, but inhibited the formation of multicellular domes in confluent cultures. LLC-PK, cells were found to have high-affinity binding sites (831 per cell) for D-factor with a dissociation constant of 197 pM.
