The current study was undertaken to compare two methods for the effici
ency of measuring tumor necrosis factor (TNF-alpha) in biological flui
ds, which is species undependent, reliable, sensitive, simple and not
expensive. We have compared the MTT tetrazolium cytotoxic assay [1, 2]
and the H-3-thymidine (H-3-TdR) incorporation cytostatic assay for me
asuring the anti-tumor activity of human recombinant TNF-alpha, of hum
an colonic tissue and of supernatants of in vitro stimulated human and
rat peritoneal macrophages. Two target cell-lines, namely murine myel
omonocytic leukaemia WEHI-164- and L-929-transformed murine fibroblast
cell-lines, were used in the MTT assay. The L-929 line was also used
in the H-3-TdR assay. WEHI-164 was more sensitive than the L-929 cell-
line in the MTT cytotoxic assay. Furthermore, the MTT assay was more s
ensitive to TNF-alpha than the H-3-TdR assay. Both methods can be used
for the detection of anti-tumor activity in biological fluids but the
MTT cytotoxic method has the advantage of being more sensitive and mo
re simple.