Breach of IL-12 monopoly in the initiation of type 1 immunity to intracellular infections: IL-12 is not required.
IL-12 is believed to play an important role in type 1 T-cell differentiation and type 1 cytokine IFN-gamma release by T- and NK-cells and macrophages in host defense against intracellular infections by bacteria, parasites, fungi and viruses. However, recent studies by us and others have provided unequivocal evidence that while IL- 12 is critically required for the development of type 1 immunity to the majority of intracellular bacterial, parasitic and fungal infections, it is not required for anti-viral type 1 immune responses. These findings have provoked our re-thinking about the role of IL-12 in type 1 immunity and the search for additional cytokines capable of initiating anti-viral type 1 immunity. We hypothesize that there exist multiple cytokines including IL-12 which play a redundant role in the initiation of type 1 immunity against viral infection. These cytokines are likely released from not only antigen-presenting macrophages/dendritic cells but many other cell types, which suits the mode of viral infection. The existence of multiple factors capable of driving type 1 immunity endows the host with additional safeguards to cope with prevalent viral foes.
Xing
Z
Z
Department of Pathology and Molecular Medicine, Center for Gene Therapeutics, Health Science Center, McMaster University, Hamilton, ON, Canada. xingz@mcmaster.ca
D000818:Animals; D001424:Bacterial Infections / Q000276:immunology; D006801:Humans; D007251:Influenza, Human / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000276:immunology*; D008216:Lymphocytic Choriomeningitis / Q000276:immunology; D009181:Mycoses / Q000276:immunology; D010272:Parasitic Diseases / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*; D014777:Virus Diseases / Q000276:immunology*
D018664:Interleukin-12; D007371:Interferon-gamma