title: Reply.
authors: Division of Gastroenterology and Hepatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors: Emanuelle
authors: E
authors: Bellaguarda
authors: Section of Gastroenterology, Hepatology and Nutrition, University of Chicago, Chicago, Illinois.
authors: Atsushi
authors: A
authors: Sakuraba
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D003424:Crohn Disease / Q000150:complications* / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D007577:JC Virus / Q000276:immunology*; D007968:Leukoencephalopathy, Progressive Multifocal / Q000453:epidemiology*; D008297:Male; D000069442:Natalizumab / Q000627:therapeutic use*
chemical_list: D000914:Antibodies, Viral; D007166:Immunosuppressive Agents; D000069442:Natalizumab