Alarming dendritic cells for allergic sensitization.
Allergic patients mount a Th2 response to common allergens, like house dust mite (HDM), pollens, molds and animal dander. Most inhaled antigens are immunologically inert, however if these antigens are accompanied by microbial or endogenous danger patterns (alarmins), they can be recognized by inflammatory cells. Dendritic cells are the most potent antigen presenting cells, which express a wide variety of receptors on their cell surface, recognizing these microbial patterns, damage induced molecules and cytokines. Dendritic cells become reporters of the microenvironment if exposed to the allergen, subsequently migrating to the draining lymph nodes where they activate naïve T lymphocytes. Dendritic cells could also be indirectly activated by epithelial cells, which express various receptors and secrete a variety of cytokines early after allergen exposure. Upon HDM exposure these cells secrete chemokines to attract monocytes and immature dendritic cells, and GM-CSF, TSLP and IL-33 to activate dendritic cells, mast cells and basophils. Danger signals which alert dendritic cells and epithelial cells comprise many proteins and molecules, contributing to an enhanced immune response to inhaled allergens. This review focuses on the role of dendritic cells and alarmins in the sensitization to inhaled allergens in allergic asthma.
Willart
Monique A M
MA
Department of Pulmonary Medicine, Laboratory of Immunoregulation en Mucosal Immunity, Ghent University, Ghent, Belgium. monique.willart@ugent.be
Hammad
Hamida
H
D000485:Allergens / Q000276:immunology*; D000818:Animals; D017951:Antigen Presentation; D001249:Asthma / Q000276:immunology* / Q000473:pathology; D002454:Cell Differentiation; D002465:Cell Movement; D016207:Cytokines; D003713:Dendritic Cells / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007114:Immunization; D008213:Lymphocyte Activation; D051192:Receptors, Pattern Recognition / Q000276:immunology*; D020545:Respiratory Mucosa / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
D000485:Allergens; D016207:Cytokines; D051192:Receptors, Pattern Recognition