Establishment of a consistent L929 bioassay system for TNF-α quantitation to evaluate the effect of lipopolysaccharide, phytomitogens and cytodifferentiation agents on cytotoxicity of TNF-α secreted by adherent human mononuclear cells

Tumor necrosis factor-α (TNF-α) plays an important role in the pathogenesis of rheumatoid arthritis. The present study was to evaluate the effects of lipopolysaccharide (LPS), phytomitogens and cytodifferentiation agents on cytotoxicity of TNF-α secreted by adherent human mononuclear cells (AMC). TNF-α cytotoxicity in LPS-treated, phytomitogen-treated, and cytodifferentiation agent-treated AMC supernatants were analyzed by the L929 bioassay system. Our results showed that LPS could induce homogeneous TNF-α production by AMC whereas, in addition to TNF-α, phytomitogens could also induce other TNF-like factors. Neither methotrexate, retinoic acid nor sodium butyrate can inhibit TNF-α cytotoxicity, while hexamethylene bisacetamide could not only inhibit TNF-α cytotoxicity but also TNF-α inducing ability of LPS to AMC.