archee at buffnet.net wrote:
>I am a new technician in an immunology lab. We do T-cell
>proliferations using thymidine. Could someone please tell me what the
>MTT assay is? I am curious. Thanks.
The MTT assay is a colormetric assay which measures (1) mitochondrial activity
and (2) cell numbers (assuming that mitochondrial activity is approximately
the same in the different test wells). It does NOT measure proliferation.
Water-soluble, yellow MTT is converted by enzymes in mitochondria to
water-insoluble, blue formazan. This occurs in living cells (active
mitochondria) but not in dead cells (no active mitochondria). The formazan
can be dissolved in isopropynol/HCL, and the optical density measured by
(multi-well) spectrophotometer. More blue = more living cells.
Within certain limits, the MTT (and related colorimetric assays) is an
accurate, fast means of determining cell number. The incubation time is about
3 hrs, and the process time varies depending on the exact chemical used (some
versions have a water-soluble product, so processing time is minimal). This
can be used in place of a thymidine incorporation assay in some cases, but
bear in mind that you get rid of the radiation only to play with some very
carcinogenic, toxic chemicals.
See article:
Mosmann, Tim. Rapid Colorimetric Assay for Cellular Growth and Survival:
Application to Proliferation and Cytotoxicity Assays.
J. Immunol. Methods 65: 55-63 (1983)
Good luck!
linda