Sensitive and simple bioassay for human tumour necrosis factor-alpha.

A simple, sensitive, and specific in vitro bioassay is described for human tumour necrosis factor alpha (TNF-alpha). The system employs the U937 cell line incubated with 10 ng/ml actinomycin D for maximum sensitivity. This method allows the detection of less than 0.6 pg/ml of TNF-alpha and the log dose-response curve is linear at concentrations 0.6-250 pg/ml TNF-alpha. Highly sensitive subclones of U937 were obtained which were capable of detecting as little as 0.1 pg/ml TNF-alpha. Finally, this bioassay demonstrates specificity by discriminating between TNF-alpha and TNF-beta.