AppliCations No. 12 Cell Proliferation Assay XTT

Cell proliferation assays are widely used in cell biology for the study of growth factors, cytokines or media components. They are also applied in the screening of cytotoxic agents and lymphocyte activation. In order to determine the number of viable cells Cell Proliferation Kit XTT employs 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt (XTT). Only in living cells mitochondria are capable to reduce XTT to form an orange colored water soluble dye. Therefore, the concentration of the dye is proportional to the number of metabolically active cells. The use of tetrazolium salts, such as MTT, commenced in the 1950s, is based on the fact that living cells reduce tetrazolium salts into colored formazan compounds.

The biochemical procedure is based on the activity of mitochondrial enzymes which are inactivated shortly after cell death. This method was found to be very efficient in assessing the viability of cells. A colorimetric method based on the tetrazolium salt, XTT, was first described by P.A. Scudiero in 1988. The use of XTT greatly simplifies the procedure of measuring proliferation, and is, therefore, an excellent solution to the quantitating of cells and their viability without using radioactive isotopes. This kit was developed to assay cell proliferation in reaction to different growth factors, cytokines and nutrient components. In addition, it is suitable for assaying cytotoxicity of materials such as TNF or other growth inhibitors. XTT can be used as a non-radioactive substitute for cytotoxic tests based on the release of 51Cr from cells with no less sensitivity.

XTT Assay Greatly Simplifies Measuring of Cell Proliferation and Viability, advantages of AppliChem Cell Proliferation Kit XTT are
• Save: without using radioactive isotopes
• Accurate: dye absorbance is proportional to the number of cells in each well
Easy-to-use: 1-step process, results within 2 - 5 hours. The Kit includes XTT reagent and activation reagent. additional reagents or cell washing procedures are not required. 
• For use in plate readers

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