[The new colorimetric assay (WST-1) for cellular growth with normal aging and Alzheimer's disease]

A new tetrazolium compound, WST-1, a sodium salt of 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate, was introduced into clinical chemistry. The compound's dehydrogenase activities are useful in the colorimetric determination of the bioreducibility of cells. It proved to have a sensitivity similar to MTT, and produces a highly colored formazan dye under reductive conditions. Compared with the MTT assay, we found the WST-1 assay to be more sensitive, more convenient, and more exact. We used the new assay to study aging-related changes in human lymphocyte blastformation. Four groups of healthy adults aged 40-49 years (N = 40), 50-59 years (N = 40), 60-69 years (N = 40), 70-76 years (N = 40) were examined. Moreover, we studied lymphocytes from 16 patients (47-74 years) with probable Alzheimer's disease. For healthy controls, a negative correlation (r = -0.3108, p < 0.05) between age and enzyme activity was noted. The regression equation was: Y = -0.0085X + 1.473 where X and Y designate the age of the individual and enzyme activity (absorbance), respectively. On the other hand, for patients with Alzheimer's disease, age and enzyme activity did not correlate. These results indicate that the WST-1 assay may be useful in the study of changes associated with aging, and also more so than the MTT assay.