TNF-alpha production as an in vitro assay predictive of cytokine-mediated toxic reactions induced by monoclonal antibodies.

When administered to patients, various biotechnology products may induce early toxic effects mediated by a cytokine cascade in which Tumor Necrosis Factor-alpha (TNF-alpha) plays a central role. The mechanisms of these toxic reactions have been extensively documented in the clinical model of the CD3 monoclonal antibody (mAb), OKT3. In order to develop a preclinical test for assessing the potential of mAbs or recombinant molecules to induce acute reactions when administered to patients, we investigated different in vitro culture systems for TNF-alpha secretion, using human blood cells. OKT3 and bacterial lipopolysaccharide (LPS) were used as positive controls. By comparing different culture conditions and kinetics, we concluded that 6-h supernatants of plasma-depleted whole blood contained high amounts of TNF-alpha in cultures stimulated by OKT3 or LPS, but not in those performed in the absence of exogenous stimulant or in the presence of mAbs which do not induce toxic reactions in vivo. This in vitro assay may be applied to the preclinical evaluation of the risk of cytokine-mediated toxicity in vivo. Owing to its simplicity, it could be used for preclinical investigation of inter-individual differences in the susceptibility to 'activation syndrome'.