Evaluation of anti-human tumor necrosis factor-alpha (anti-hTNF-α) antibody production in TNF-α transgenic (TTg) mice immunized with TNF kinoid (TNF-K). TTg mice were immunized at 15, 16, and 19 weeks of age (open arrows) with TNF-K. (a) Enzyme-linked immunosorbent assay of anti-hTNF-α antibodies. (b) The neutralizing capacity of the anti-hTNF-α antibody was evaluated on L929 cells and is expressed as the mean of the reciprocal of the serum dilution that neutralizes 50% of hTNF-α activity (NC50). Closed histograms represent mice that did not receive the TNF-K maintenance dose (TNF-K without md) at 32 weeks of age (shaded arrow). Open histograms represent mice that did receive it (TNF-K with md). Results are expressed as mean ± standard error of the mean. *P < 0.05.