Hemin dependent morphological maturation and endogenous porphyrin synthesis by K562 leukemic cells.

The alterations in the morphological phenotypes of K562 cells induced by exogenous hemin, and its effect on porphyrin accumulation was analyzed by scanning electron microscopy and flow cytometry. The morphology of the uninduced cells was mainly of microvilli, blebi and ruffle covered cells, while after hemin induction the fraction of the blebi-cells increased and smooth erythroid-like cells appeared. The large variations in cell-volume of the cells were decreased only marginally after hemin treatment. Porphyrin fluorescence revealed a marked accumulation of endogenous porphyrins after induction by hemin.