title: [Macrophage activation syndrome secondary to tocilizumab: Myth or reality?].
abstract: BACKGROUND
  Some authors have reported macrophage activation syndrome (MAS) secondary to infusion of tocilizumab, a monoclonal antibody that blocks interleukin-6 (IL-6). The pathophysiology of MAS is however linked to uncontrolled activation of innate immunity, mediated in part by IL-6. We conducted a study for macrophage activation biomarkers in a cohort of patients treated with tocilizumab.
  
  
  RESULTS
  Twenty-seven patients were included prospectively in our center. Levels of neutrophils, platelets, CRP and fibrinogen were lower at the end of treatment than at initiation (P<0.05); other biomarkers were stable. There was neither clinical sign of SAM nor hemophagocytosis in myelogram.
  
  
  CONCLUSIONS
  Laboratory abnormalities are related to direct blockade of IL-6 by tocilizumab and decrease hepatic protein synthesis. Tocilizumab is not responsible for MAS and associations described are more likely to be related to the autoimmune underlying disease, rather than treatment.
authors.affiliation: Clinique universitaire de médecine interne, CHU de Grenoble, 38000 Grenoble, France; Université Joseph-Fourier, Grenoble-1, 38000 Grenoble, France. Electronic address: aderoux@chu-grenoble.fr.
authors.forename: A
authors.initials: A
authors.lastname: Deroux
authors.affiliation: Clinique universitaire de médecine interne, CHU de Grenoble, 38000 Grenoble, France.
authors.forename: F
authors.initials: F
authors.lastname: Andry
authors.affiliation: Clinique universitaire de médecine interne, CHU de Grenoble, 38000 Grenoble, France; Université Joseph-Fourier, Grenoble-1, 38000 Grenoble, France.
authors.forename: L
authors.initials: L
authors.lastname: Bouillet
mesh_terms: D000328:Adult; D061067:Antibodies, Monoclonal, Humanized / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D006801:Humans; D055501:Macrophage Activation Syndrome / Q000139:chemically induced*; D008875:Middle Aged; D011446:Prospective Studies; D000093242:Interleukin-6 Inhibitors; D015850:Interleukin-6
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D015415:Biomarkers; D000093242:Interleukin-6 Inhibitors; C508600:IL6 protein, human; D015850:Interleukin-6; C502936:tocilizumab
keywords: Arthrite juvénile idiopathique; Blocage IL6; Cytopenias; Cytopénies; IL-6 blockade; Juvenile idiopathic arthritis; Macrophage activation syndrome; Syndrome d’activation macrophagique; Tocilizumab