Danger signals: SOS to the immune system.
The activation of dendritic cells, necessary for the initiation of primary and secondary immune responses, can be induced by endogenous danger signals - released by tissues undergoing stress, damage or abnormal death - and also by exogenous danger signals elaborated by pathogens. Some endogenous danger signals that recently have been discovered are heat-shock proteins, nucleotides, reactive oxygen intermediates, extracellular-matrix breakdown products, neuromediators and cytokines like the IFNs. We propose that allergy may be initiated by the direct damage of dendritic or other cells by toxic chemicals and allergenic proteases, and suggest that the triggering of danger signal receptors by exogenous pathogen-derived molecules may be more to the advantage of the pathogen than to the host.
Gallucci
S
S
Ghost Laboratory, Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 4, Room 111, Bethesda, MD 20892, USA. sgallucci@niaid.nih.gov
Matzinger
P
P
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000382:microbiology; D006801:Humans; D007107:Immune System / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D018448:Models, Immunological; D015398:Signal Transduction / Q000276:immunology*