SIMPLE COLORIMETRIC CELL-CELL ADHESION ASSAY USING MTT-STAINED LEUKEMIA-CELLS

A new and simple method for quantitating adhesion of leukemia cells, H L60, to endothelial cells was developed. HL60 cells were incubated wit h MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) which forms a blue dye of formazan in the cells. MTT did not inhibit s hape change of HL60 cells induced on activated endothelial cells at 90 min. The expression of a cell adhesion molecule, LFA-1, in HL60 cells at 21 h was not inhibited by MTT. After incubation of the MTT-labeled cells and endothelial cells, non-adhered cells were washed out. Adher ed cells were lysed with dimethylsulfoxide, and quantitated by measuri ng absorbance at 540 nm. The absorbance was well correlated with the a dherent cell numbers measured by direct counting or by Cr-51-labeling method. U937 and Ramos cells were also quantitatively labeled by MTT. The method has the advantage of being easy, simple and applicable to v arious cell-cell adhesion assays.