The Body’s Immune Responses to Food-Related Pathogens and Allergens Flashcards
(45 cards)
What is innate immunity
• Immediate, non-specific defense present from birth.
• Recognizes common danger signals and responds rapidly (within minutes).
• No memory; does not improve with repeated exposure.
• Components: granulocytes (neutrophils, eosinophils, basophils), monocytes/macrophages, natural killer cells.
What is adaptive immunity
• Not present from birth; develops after exposure to antigens.
• Highly specific and sophisticated recognition systems.
• Slower response (days), but forms immunological memory.
• Components: T cells, B cells, antibodies.
• Gut-Associated Lymphoid Tissue (GALT) plays a key role in food-related immunity.
What are the cells of the innate immune system
Granulocytes (Neutrophi, Eosinophil, basophil)
Natural killer cells
Monocytes/macrophages
What is the main function of neutrophils
Phagocytosis
What is the main fcuntion of eosinophils
Destroy parasites
What is the function of basophils
Inflammation
Which type of granulocytes makes up>90% of granulocytes
Neutrophils
What are natural killer cells
Natural killer cells are extracellular killers and act by releasing perfornin into the infected cell, which then goes on to commit cell suicide (apoptosis)
What is the role neutrophils and monocytes/macrophages
Neutrophils and monocytes/macrophages are phagocytes and act by eating the infected/damaged tissue
What are the antigen presenting cells
Macrophages, b cells and dendritic cells
Dendritic cells and macrophages present antigens to T helper cells via MHC II, initiating adaptive immune responses.
What are the acquired/adaptive immune system responses
• Cell-mediated and humoral responses: T helper cells coordinate responses; B cells differentiate into plasma cells that secrete antibodies (immunoglobulins, Ig).
• Both T and B cells generate memory cells, improving defense upon repeated exposure.
When is an acquired immune response initiated
An acquired immune response is initiated when a macrophage or dendritic cell (APC’s) present antigen proteins to T helper cells as the MHC II
What helps to coordinate an immune response specific to the antigen presented
T helper cells help to co-ordinate an immune response that is specific to the antigen presented
What is the function of b cells
Activated B cells bind antigen and proliferate into plasma cells that secrete vast amounts of antibody specific to the antigen
These antibodies are secreted immunoglobulins (Ig) that circulate body fluids
Which type of cell exhibit memory cells
Both T and b cells
What happens to the acquired immune system with repeated exposure
Improves
What are the mechanisms of response to bacterial toxins
• Pathogen recognition via pattern recognition receptors (PRRs) like TLRs.
• Inflammatory cytokines: IL-1, IL-6, TNF-α.
• Neutralizing antibodies (especially IgA) bind pathogens/toxins, preventing cell entry and aiding in destruction.
Which 3 cytokines are involved in cell mediated immune responses
IL-1, IL-6 and TNF-α
What is the function of toll-like receptors
Recognise danger signals and are stimulated to cause a response and activate T-cells via antigen presenting system to release cytokines
What is the role of neutralising antibodies
• Bind bacterial/viral surfaces or toxins, preventing their interaction with host cells.
• Facilitate pathogen destruction by macrophages.
• Example: IgA is the main antibody at mucosal surfaces, neutralizing pathogens and toxins, and is abundant in early milk (colostrum) for neonatal protection.
What are the functions of IgA
Inhibition of microbial adherence to mucosal cells
Neutralise toxins and pathogens
Prevent commensal bacteria from entering bloodstream
Present in early milk–> intestinal protection of neonate
What is the most abundant Ig around mucosal membrane
IgA
How does IgA access the gut lumen
- IgA produced by BCells
- Dimeric IgA binds to polymeric Ig receptor on epithelial cells, is transported into gut lumen through epithelial cells at base of crypts
- dimericap IgA binds to the layer of mucus overlying the gut epithelium, secretory
component still attached to IgA attaches to
mucins in mucus - IgA in the gut neutralises pathogens and their toxins
What are the mechanisms in response to viruses
Immune response:
• Interferon (IFN-α/β) production: induces antiviral states, fever, and pain reduction.
• Secretory IgA neutralizes viruses at mucosal surfaces.
• Activation of cytotoxic CD8+ T cells (CTLs): recognize infected cells via MHC I, kill them via perforin and granzyme release.
