1Gamal E. Eid and 2Sameh E. El-Shewemi.
1Microbiology
& Immunology Unit and 2Histology & Electron Microscopy Unit
Department of Clinical Laboratory Sciences, College of Applied Medical
Sciences, King Saud University, Riyadh.
Tumor necrosis
factor-alpha (TNF-a) is one of the
major cytokines regulating a large spectrum of physiological and
pathophysiological functions of the immune system. In this investigation, a
colourimetric microassays and electron microscopy were used to study the
cytotoxic effect of TNF-a on WEHI-13 VAR
(mouse fibrosarcoma) as tumor target cells. Water-soluble tetrazolium (MTS/PMS)
reduction as well as crystal violet (CV) staining assays were used to detect
the cytotoxic activity induced by different TNF-a concentrations (1, 10, 100, 1000, and 10,000 pg/ml) and incubation
times (0, 1, 2, 4, 6, 9, and 20 hours). Cytotoxicity started to develop after 9
hrs of incubation and reached 100 % at 10,000 pg/ml after 20 hrs of incubation
when detected by MTS/PMS assay and 86.1 % when detected by CV assay. Although,
the MTS/PMS method expressed higher sensitivity than CV staining assay, the
percentage of cytotoxicity induced by TNF-a was directly correlated to each other when detected by both
colourimetric assays. The ultrastructural changes induced by TNF-a on target cells were mainly cytoplasmic
rather than nuclear. These changes were also dependent on the dose and / or
duration of exposure to TNF-a.