Determination of Multidrug Resistance of Human KB Carcinoma Cells by MTT Colorimetric Assay

To determine the relative resistances of KB A 1 cells to the parent cell line KB 3 1,MTT colorimetric assay was used to evaluate the cell growth and survival.In the experiment,It was found that the serum can affect the result of MTT assay,and the optical density reached the maximum with the serum concentration of w =0.02,and the minimum with w =0.30.While at the concentrations between w =0.05~0.20 it fluctuated a little.When no serum was added,the formazan product could not be easily dissolved and the error was inevitably introduced.So,in the ordinary range around w =0.10,the addition of serum to the reaction medium will not cause error to the MTT assay and the experiment can be done easily.This MTT assay was used to perform drug sensitivity assays of KB 3 1 and its drug resistant mutant,KB A 1.The relative resistances of KB A 1 to colchicine,vinblastine and adriamycin are 137,45 and 167 respectively compared with KB 3 1.