title: New twist on an ancient innate immune pathway.
abstract: Activation of the complement system has long been known to be regulated by a series of steps involving fluid-phase convertases. In this issue of Immunity, Liszewski et al. (2013) report the discovery of an intracellular cathepsin-L-dependent C3 activation pathway.
authors: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors: Stephane
authors: S
authors: Lajoie
authors: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA. Electronic address: mwkarp@jhsph.edu.
authors: Marsha
authors: M
authors: Wills-Karp
mesh_terms: D016175:B-Lymphocyte Subsets / Q000166:cytology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D056668:Cathepsin L / Q000378:metabolism*; D002454:Cell Differentiation; D003167:Complement Activation / Q000502:physiology*; D003176:Complement C3 / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology*; D006801:Humans
chemical_list: D003176:Complement C3; C534281:CTSL protein, human; D056668:Cathepsin L