Mucosal Immunity Flashcards
Mucosal immunity:
The immune response that protects the mucosal surfaces (e.g., gut, respiratory tract, urogenital tract) from pathogens while maintaining tolerance to non-harmful antigens.
Mucosal-associated lymphoid tissues (MALT):
Lymphoid tissues found at mucosal surfaces, including the tonsils, Peyer’s patches, and other lymphoid follicles.
Peyer’s patches:
Specialized areas of MALT in the small intestine that sample antigens and initiate immune responses.
Mucosal surfaces:
Sites exposed to the external environment, including the respiratory, gastrointestinal, and urogenital tracts, where pathogens are commonly encountered.
IgA antibodies:
The main antibody isotype produced at mucosal sites, secreted into the mucus to neutralize pathogens and prevent them from entering the body.
Secretory IgA (sIgA):
A dimeric form of IgA found in mucosal secretions that provides immune protection at mucosal surfaces.
Dendritic cells in mucosal immunity:
Capture and process antigens at mucosal surfaces, then migrate to lymph nodes to activate T and B cells.
M cells:
Specialized epithelial cells in MALT that transport antigens from the lumen to underlying immune cells, initiating immune responses.
T-cell responses in mucosal immunity:
T cells in mucosal tissues (e.g., Th17, Treg cells) regulate the immune response and maintain tolerance to harmless antigens.
Th17 cells in mucosal immunity:
Helper T cells that promote inflammation and defense against extracellular pathogens, especially at mucosal surfaces.
Regulatory T cells (Tregs) in mucosal immunity:
Help maintain immune tolerance at mucosal surfaces, preventing inappropriate immune responses to harmless antigens.
Mucosal tolerance:
The immune system’s ability to ignore non-pathogenic antigens at mucosal sites, such as food proteins and commensal bacteria.
Oral tolerance:
Immune tolerance induced through oral exposure to antigens, preventing immune responses to food and gut microbiota.
Gut-associated lymphoid tissue (GALT):
A type of MALT located in the gastrointestinal tract, involved in sampling antigens and initiating immune responses.
Lung-associated lymphoid tissue (LALT):
A type of MALT found in the respiratory tract, where immune responses to inhaled pathogens are initiated.
Mucosal vaccination:
Vaccines designed to stimulate mucosal immunity, often using oral or nasal routes, to provide protection against infections at mucosal surfaces.
Commensal microbiota and mucosal immunity:
The normal flora in mucosal tissues that help protect against pathogens by competing for resources and stimulating immune responses.
Antigen sampling by MALT:
Antigens from the external environment are captured by cells in MALT (e.g., M cells, dendritic cells) and presented to immune cells to initiate an immune response.
Intraepithelial lymphocytes (IELs):
T cells located in the epithelial layer of mucosal tissues that play a role in immune defense and tissue homeostasis.
Mucosal immune responses to pathogens:
Rapid and efficient immune responses at mucosal surfaces involving IgA production, T cell activation, and inflammatory responses.
Mucosal immunization and memory:
Immunization via mucosal routes generates long-lasting immunity at mucosal sites, providing protection upon re-exposure to pathogens.
Mucosal inflammation:
Inflammatory responses at mucosal surfaces caused by infection or injury, leading to symptoms like swelling, redness, and pain.
Toll-like receptors (TLRs) in mucosal immunity:
Pattern recognition receptors on mucosal immune cells that recognize microbial patterns and trigger immune responses.
Mucosal immune defense mechanisms:
Include physical barriers (mucus, epithelial cells), innate immunity (complement, antimicrobial peptides), and adaptive immunity (IgA, T cells).
Epithelial cell function in mucosal immunity:
Epithelial cells act as a physical barrier and secrete antimicrobial peptides and cytokines to defend against pathogens.
Mucosal vaccines (e.g., oral polio vaccine):
Designed to stimulate IgA production at mucosal surfaces to prevent pathogen entry and infection at these sites.
Induction of mucosal immune responses:
Involves antigen uptake by specialized cells (e.g., dendritic cells, M cells) and the activation of local T and B cells at mucosal tissues.
Immune exclusion:
The process by which IgA antibodies prevent pathogens from adhering to and invading epithelial cells at mucosal surfaces.
Mucosal immunity and allergy:
Defects in mucosal immune regulation can contribute to allergic diseases, such as allergic rhinitis or asthma, where inappropriate immune responses are triggered.
