A. Levesque et al., IMPROVED FLUORESCENT BIOASSAY FOR THE DETECTION OF TUMOR-NECROSIS-FACTOR ACTIVITY, Journal of immunological methods, 178(1), 1995, pp. 71-76
Tumor necrosis factor alpha (TNF-alpha) is a monokine of 17 kDa produc
ed by activated macrophages and various cells involved in the immune s
ystem. We propose a new method for the measurement of TNF activity on
mouse L929 fibroblast cells. After an incubation with TNF, the cells w
ere stained with a solution of ethidium homodimer-1, a high-affinity r
ed fluorescent DNA dye that is internalized only through altered cell
membranes. The assay is sensitive, inexpensive and correlates with the
already reported TNF assays while measuring the membrane alteration b
y TNF and not the cell detachment. It requires no rinsing before dye a
ddition which may cause cell loss; there is no interference with cultu
re medium components since the assay is performed in PBS. This method
is more rapid and precise for routine measurement of TNF activity.