Clinical evaluation of human tumor necrosis factor-alpha transgenic (TTg) mice immunized with tumor necrosis factor kinoid (TNF-K) or phosphate-buffered saline (PBS) or treated with infliximab (IFX). TTg mice were immunized with TNF-K or PBS emulsified in ISA-51 adjuvant or were IFX-treated. All mice were monitored for clinical signs of arthritis and for weight for 18 or 36 weeks. (a) TTg mice received three primary injections at 15, 16 and 19 weeks of age (open arrows) of TNF-K (n = 15, open and closed diamonds) or PBS (n = 8, squares). At 32 weeks of age (shaded arrow), TTg mice received a maintenance dose (md) of TNF-K (n = 7, open diamonds) or an injection of PBS emulsified in ISA-51 adjuvant (n = 8, closed diamonds). Eight TTg mice (circles) received weekly intraperitoneal injections of IFX (bold arrows) from week 15 for a period of 12 weeks (until 27 weeks of age). (b) The weight gain of all groups is represented. Results are expressed as mean ± standard error of the mean. *P < 0.05 versus PBS.