GENERATION OF A MOUSE-TUMOR NECROSIS FACTOR MUTANT WITH ANTIPERITONITIS AND DESENSITIZATION ACTIVITIES COMPARABLE TO THOSE OF THE WILD-TYPEBUT WITH REDUCED SYSTEMIC TOXICITY

In this study, me investigated whether the recently identified lectin- like domain of tumor necrosis factor (TNF) is implicated in its biolog ical activities on mammalian cells, To this end, a mouse TNF (mTNF) tr iple mutant, T104A-E106A-E109A mTNF (referred to hereafter as triple m TNF), lacking the lectin-like affinity of mTNF for specific oligosacch arides, was compared with the wild-type molecule for various TNF effec ts in vitro and in vivo. The triple mTNF displayed a 50-fold-reduced T NF receptor 2 (TNFR2)-mediated bioactivity but only a 5-fold-reduced T NFR1-mediated bioactivity in vitro. The specific activity of the tripl e mutant on L929 fibrosarcoma cells was slightly reduced compared with that of the wild type. We subsequently assessed the systemic toxicity of triple versus wild-type mTNF, since TNFR2 is partially implicated in this activity. The triple mTNF had a significantly reduced toxicity compared with that of wild-type mTNF in vivo. Moreover, we compared t he effects of the triple and the wild-type mTNFs in TNFR1-mediated phe nomena, such as (i) induction of tolerance towards a lethal mTNF dose and (ii) protective activity in cecal ligation and puncture-induced se ptic peritonitis, No significant differences between the mutant and wi ld-type forms were observed. In conclusion, these results indicate tha t triple mTNF, lacking TNF's lectin-like binding capacity, has reduced systemic toxicity but retains the tolerance-inducing and peritonitis- protective activities of wild-type mTNF.