Life Science Research Laboratories, Asahi Chemical Industry Co., Ltd., Shizuoka, Japan.
The methods in general use for quantifying leukemia inhibitory factor (LIF) activity involve measurements of suppression of proliferation or stimulation of phagocytic activity of mouse myelocytic leukemia (M1) cells. We have developed a novel assay for LIF activity which consists of measuring MTT reduction by M1 cells. The ability of M1 cells to reduce MTT correlates with the level of LIF used for stimulation. The MTT assay of LIF is much quicker than previously used quantitation methods and it is just as sensitive. The MTT assay can also be used to quantify IL-6.