GAMMA-INTERFERON UP-REGULATES TRANSFERRIN RECEPTORS AND DECREASES MEMBRANE MICROVISCOSITY IN K562 CELLS

We investigated the effect of gamma-interferon (gamma-IFN) on three ce llular parameters: cell membrane fluidity and expression of two antige ns that have been associated with cell proliferation, namely transferr in receptor (Tf-R: a cell surface protein) and Ki-67 antigen (Ki-67: a nuclear protein). We observed small, yet significant changes in the f irst two parameters, but not the third parameter. These were investiga ted in K562 cells, a human chronic myelocytic leukemia cell line. Thes e results suggest that the microviscosity changes and the surface Tf-R density were closely associated, and that gamma-IFN was involved in i ncreasing proliferative activity of the cells by decreasing membrane f luidity and upregulating Tf-R expression.