title: Mechanisms for cytotoxic effects of anti-tumor necrosis factor agents on transmembrane tumor necrosis factor alpha-expressing cells: comparison among infliximab, etanercept, and adalimumab.
abstract: OBJECTIVE
  Three anti-tumor necrosis factor alpha (anti-TNFalpha) agents have been proved to be effective for rheumatoid arthritis (RA) and other inflammatory disorders. Infliximab and adalimumab have been generated as anti-TNFalpha monoclonal antibodies, while etanercept is engineered from human type II TNF receptors. In spite of all 3 agents' equal efficacy for RA, both infliximab and adalimumab are effective for other diseases such as Crohn's disease and Wegener's granulomatosis, while etanercept is not. We undertook this study to understand the different clinical effects of these anti-TNFalpha agents by analyzing their biologic activities on transmembrane TNFalpha.
  
  
  METHODS
  Jurkat T cells stably expressing an uncleavable form of transmembrane TNFalpha were used for the following studies: 1) flow cytometric analysis of binding activities of anti-TNF agents to cell surface transmembrane TNFalpha, 2) complement-dependent cytotoxicity (CDC), 3) antibody-dependent cell-mediated cytotoxicity (ADCC) by using peripheral blood mononuclear cells, and 4) outside-to-inside (reverse) signal transduction through transmembrane TNFalpha estimated by apoptosis and cell cycle analysis using flow cytometry.
  
  
  RESULTS
  All of the anti-TNFalpha agents bound to transmembrane TNFalpha. Infliximab and adalimumab exerted almost equal CDC activities, while etanercept showed considerably lower activity. ADCC activities were almost equal among these 3 agents. Adalimumab and infliximab induced apoptosis and cell cycle arrest in transmembrane TNFalpha-expressing Jurkat T cells, reflecting an outside-to-inside signal transduction through transmembrane TNFalpha.
  
  
  CONCLUSIONS
  Three different anti-TNF agents showed different biologic effects on transmembrane TNFalpha. This finding suggests that CDC and outside-to-inside signals by anti-TNFalpha antibodies may explain the successful clinical efficacy of adalimumab and infliximab in Crohn's disease and Wegener's granulomatosis.
authors.affiliation: Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Mitoma
authors.forename: Takahiko
authors.initials: T
authors.lastname: Horiuchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsukamoto
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tamimoto
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kimoto
authors.forename: Ayumi
authors.initials: A
authors.lastname: Uchino
authors.forename: Kentaro
authors.initials: K
authors.lastname: To
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Harashima
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Hatta
authors.forename: Mine
authors.initials: M
authors.lastname: Harada
mesh_terms: D000068879:Adalimumab; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D002478:Cells, Cultured; D000068800:Etanercept; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology*; D000069285:Infliximab; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000096:biosynthesis*
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab; D000068879:Adalimumab; D000068800:Etanercept