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Questions and Answers
What occurs approximately 6 hours after the immediate response in the lungs?
What occurs approximately 6 hours after the immediate response in the lungs?
What type of allergic reaction is associated with swelling and redness in the skin?
What type of allergic reaction is associated with swelling and redness in the skin?
In sensitization to inhaled allergens, what first happens to the allergen particles in the airways?
In sensitization to inhaled allergens, what first happens to the allergen particles in the airways?
Which response leads to the production of IgE antibodies?
Which response leads to the production of IgE antibodies?
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What is the primary consequence of IgE binding to mast cells upon a second exposure to an allergen?
What is the primary consequence of IgE binding to mast cells upon a second exposure to an allergen?
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What are immune complexes formed by?
What are immune complexes formed by?
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What type of immune response is triggered by nickel exposure?
What type of immune response is triggered by nickel exposure?
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Which cells are primarily involved in the delayed-type hypersensitivity reaction to poison ivy?
Which cells are primarily involved in the delayed-type hypersensitivity reaction to poison ivy?
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What characterizes the immediate response in IgE-mediated allergic reactions?
What characterizes the immediate response in IgE-mediated allergic reactions?
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How long does it typically take for a delayed reaction to occur after exposure in a type IV hypersensitivity?
How long does it typically take for a delayed reaction to occur after exposure in a type IV hypersensitivity?
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What is one of the measurements used to assess the response during an asthmatic reaction?
What is one of the measurements used to assess the response during an asthmatic reaction?
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What causes the late-phase response in IgE-mediated allergic reactions?
What causes the late-phase response in IgE-mediated allergic reactions?
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What condition may result from the deposition of immune complexes in blood vessel walls?
What condition may result from the deposition of immune complexes in blood vessel walls?
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What is the role of IgE in allergic reactions and parasitic infections?
What is the role of IgE in allergic reactions and parasitic infections?
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How does the first exposure to an allergen differ from subsequent exposures?
How does the first exposure to an allergen differ from subsequent exposures?
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What characterizes Type I hypersensitivity reactions?
What characterizes Type I hypersensitivity reactions?
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What type of hypersensitivity is characterized by the immune response to drugs that modify cell surface components?
What type of hypersensitivity is characterized by the immune response to drugs that modify cell surface components?
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Which of the following best defines an allergen?
Which of the following best defines an allergen?
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What is the mechanism that causes tissue damage in Type III hypersensitivity?
What is the mechanism that causes tissue damage in Type III hypersensitivity?
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What term describes individuals with a predisposition to allergic reactions?
What term describes individuals with a predisposition to allergic reactions?
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What triggers the degranulation of mast cells during an allergic reaction?
What triggers the degranulation of mast cells during an allergic reaction?
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What initiates the secondary adaptive immune response upon subsequent exposure to an allergen?
What initiates the secondary adaptive immune response upon subsequent exposure to an allergen?
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Which cells are primarily activated during an immediate hypersensitivity reaction?
Which cells are primarily activated during an immediate hypersensitivity reaction?
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What is primarily obstructed in allergic rhinitis?
What is primarily obstructed in allergic rhinitis?
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Which symptom is NOT commonly associated with allergic rhinitis?
Which symptom is NOT commonly associated with allergic rhinitis?
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What is the primary cause of shortness of breath in allergic asthma during an acute response?
What is the primary cause of shortness of breath in allergic asthma during an acute response?
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What leads to the chronic response in allergic asthma?
What leads to the chronic response in allergic asthma?
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What is the role of histamine in allergic reactions?
What is the role of histamine in allergic reactions?
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Which cells are primarily involved in the infiltration during allergic asthma?
Which cells are primarily involved in the infiltration during allergic asthma?
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What causes the wheal-and-flare reaction observed in allergic responses?
What causes the wheal-and-flare reaction observed in allergic responses?
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What is a major consequence of chronic inflammation in allergic asthma?
What is a major consequence of chronic inflammation in allergic asthma?
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What is the primary consequence of mast cell activation in anaphylaxis?
What is the primary consequence of mast cell activation in anaphylaxis?
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Which of the following can trigger gastrointestinal allergic reactions?
Which of the following can trigger gastrointestinal allergic reactions?
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What is the purpose of desensitization as a treatment option for allergies?
What is the purpose of desensitization as a treatment option for allergies?
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What typifies a helminth parasite?
What typifies a helminth parasite?
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What are ectoparasites primarily characterized by?
What are ectoparasites primarily characterized by?
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What triggers the release of granules from mast cells during a parasitic infection?
What triggers the release of granules from mast cells during a parasitic infection?
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Which of the following symptoms can result from food allergies?
Which of the following symptoms can result from food allergies?
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What is an effect of systemic allergic reactions like anaphylaxis?
What is an effect of systemic allergic reactions like anaphylaxis?
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What role does IL-5 play in parasitic infections?
What role does IL-5 play in parasitic infections?
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What are protozoa primarily characterized by?
What are protozoa primarily characterized by?
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How do eosinophils participate in the immune response against parasites?
How do eosinophils participate in the immune response against parasites?
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What is the primary danger associated with severe systemic allergic reactions?
What is the primary danger associated with severe systemic allergic reactions?
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What is a consequence of the mediators released by mast cells during parasitic infection?
What is a consequence of the mediators released by mast cells during parasitic infection?
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What is the main function of IgE during a parasitic infection?
What is the main function of IgE during a parasitic infection?
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During a parasitic infection, what happens to B cells after they are activated by Th2 cells?
During a parasitic infection, what happens to B cells after they are activated by Th2 cells?
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What type of cells do eosinophils express Fc receptors for during parasitic infections?
What type of cells do eosinophils express Fc receptors for during parasitic infections?
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Study Notes
Allergy and Immune Response to Parasites
- Immunology course, BIO 371
- Instructor: Dr. Amro Soliman
- Contact information provided
Allergens
- Allergens are harmless substances that trigger allergic reactions in sensitive individuals
- Examples of allergens include:
- Inhaled: pollen, dust mites
- Injected: insect venom, drugs
- Ingested: peanuts, shellfish
- Contacted: plant oil, metal
Immune Responses to Allergens and Parasites
- Allergic and parasitic infections share similar immune responses
- The main antibody involved in allergic reactions and parasitic infections is IgE
- IgE does not directly bind to antigens (Ag) alone
- IgE binds to Fc receptors on mast cells, basophils, and eosinophils
- IgE bound to these cells recognizes and binds to antigens
- This triggers the release of inflammatory mediators, such as histamine
- This promotes inflammation and helps kill parasites
Types of Hypersensitivity Reactions
- Classified according to effector mechanisms:
- Type I: Immediate hypersensitivity (e.g., contact allergies, asthma)
- Type II: Antibody-mediated hypersensitivity (e.g., drug reactions)
- Type III: Immune complex-mediated hypersensitivity (e.g., serum sickness)
- Type IV: Cell-mediated hypersensitivity (e.g., poison ivy reaction)
Type I Hypersensitivity
- Primary adaptive immune response generates IgE specific to the allergen
- IgE circulates and binds to Fc receptors on mast cells, basophils, and eosinophils
- Subsequent exposure triggers degranulation and release of inflammatory mediators (e.g., histamine)
- This leads to immediate hypersensitivity reactions
Type II Hypersensitivity
- Immune response to chemically reactive small molecules (e.g., drugs)
- Modifies cell surface components (self-antigens), making them foreign
- B cells produce IgG against new epitopes
- IgG triggers complement activation and opsonization
- Leading to inflammation and tissue damage
Type III Hypersensitivity
- Caused by therapeutic antibodies from animals (e.g., mice)
- Animal antibodies are recognized as foreign antigens (Ag)
- Human antibodies bind to animal antibodies forming immune complexes
- These complexes deposit in blood vessels and alveoli, activating complement system
- Leading to inflammation and severe disease (serum sickness)
Type IV Hypersensitivity
- Allergic immune response to metals (e.g., nickel)
- Modified peptides are recognized as foreign antigens by dendritic cells (DCs) and T cells
- Activates CD4 T cells, triggering an adaptive immune response
- Leading to inflammation and tissue damage, including redness, itchiness, and blistering
- Delayed-type hypersensitivity (DTH) as it takes 24-72 hours to develop
IgE-Mediated Allergic Reactions
- Consist of an immediate response followed by a late-phase response, for instance, in contact allergic reactions.
- Immediate: Within minutes following exposure (e.g., wheal-and-flare reactions mediated by IgE).
- Late-phase: 6–8 hours after exposure (more swelling induced by cytokines, chemokines, and inflammatory cells lasting for a longer period).
Physical Effects of IgE-Mediated Mast-Cell Degranulation
- Vary based on the tissue exposed to allergens.
- Gastrointestinal tract: increased fluid secretion, expulsion of tract contents.
- Airways: decreased diameter, mucus secretion, coughing, sneezing
- Blood vessels: increased blood flow, increased permeability, edema, inflammation
- Skin: swelling, redness
- Everywhere: Anaphylaxis symptoms
Allergic Diseases of the Respiratory Tract
- Nasal cavity: allergic rhinitis
- Lower respiratory airways: asthma.
- Diagrams of respiratory system are present
Sensitization to Inhaled Allergens
- Airborne particles get caught in mucus and are broken down
- Antigen peptides are presented by antigen-presenting cells (APCs) to T cells
- This stimulates Th2 response, leading to IgE production
- IgE binds to mast cells
Allergic Rhinitis
- Local edema and nasal discharge are observed
- Discharge is rich in eosinophils
- Associated with irritation, itchiness, and sneezing
Allergic Asthma: Acute Response
- Activation of mucosal mast cells (upon allergen exposure), leads to severe effects
- Including shortness of breath and wheezing
- Mediators from mast cells cause infiltration of Th cells, neutrophils and mast cells
- Resulting in further inflammation within lung tissues
Allergic Asthma: Chronic Response
- Frequent allergen exposure leads to chronic inflammation
- Continuous release of cytokines instigates further inflammation (a vicious cycle)
- Airways are blocked by mucus for a prolonged period
Skin
- Structure of skin layers is visualized
Wheal-and-Flare Reaction
- Histamine dilates blood vessels, causing fluid and protein leakage (swelling), and redness.
Skin Allergic Reactions
- Urticaria/hives (superficial)
- Angioedema (subcutaneous tissue edema)
Gastrointestinal Tract
- Diagram of digestive system is available
Ingestion of Food/Drugs
- Certain foods and drugs (e.g., peanuts, penicillin, aspirin) can cause allergies
- Allergens trigger intestinal smooth muscle contraction, causing local symptoms
- Systemic symptoms (urticaria) can occur if allergens diffuse into the bloodstream.
Anaphylaxis
- Severe systemic allergic reaction
- Mediated by mast cell activation throughout the body
- Leads to various tissue-specific effects, resulting in shock and/or respiratory compromise
- Death can occur
Prevention and Treatment
- Avoid allergens
- Drugs (antihistamines, steroids)
- Desensitization therapy (allergy shots)
Parasites
- Organisms that live on or inside the host.
- Cause chronic diseases by competing with the host for nutrients and inducing tissue damage
- Classified into three major groups:
- Protozoa (single-celled organisms), e.g., Plasmodium, Giardia
- Helminths (worm-like multicellular parasites), e.g., nematodes, trematodes, cestodes
- Ectoparasites (live on the surface of the host), e.g., fleas, lice, ticks, mites
Worldwide Distribution of Parasitic and Allergic Diseases
- Maps showing global distribution
Tenets of the Hygiene Hypothesis
- Excessive hygiene reduces childhood exposure to microorganisms
- This reduces immune system development and exposure to real-world illnesses, leading to allergies
Immune Response to Parasites
- B cells recognize parasitic antigens, process them and present to Th2 cells.
- Th2 cells activate B cells and release cytokines, leading to B cell activation, somatic hypermutation, and class switching to IgE.
- This results in the production of IgE-secreting plasma cells, providing a humoral response.
- IgE also targets parasites
How IgE Fight Parasitic Infections
- IgE does not bind to antigens alone.
- IgE binds to Fc receptors on mast cells, basophils, and eosinophils.
- IgE bound to Fc receptors binds to parasite antigens, stimulating degranulation (release of granules).
- Granules release mediators (e.g., histamine, proteases) killing parasites and causing local inflammation and collateral tissue damage
- Inducing muscle spasms and diarrhea to eliminate parasites.
IL-5, a Major Cytokine in Parasitic Infections
- Th2 cells secrete IL-5
- Crucial for eosinophil development and function
- Increase eosinophils in blood and infected tissues
- Eosinophils express Fc receptors to bind to IgE associated with parasitic antigens and stimulate degranulation to kill the parasites
Mediators Produced by Eosinophils
- Eosinophils produce various molecules including enzymes, toxins, and mediators
- These molecules kill parasites, induce histamine release, remodel connective tissue, and increase vascular permeability.
Mast Cells in Allergic and Anti-Parasitic Responses
- Mast cells display a high number of Fc receptors armed with different IgE specificities.
- Can also be armed with IgE specific to parasites (blood fluke, hookworm, roundworm) and allergens (pollen, peanuts, cat dander, bee venom)
Basophils
- Similar function as mast cells, and express Fc receptors for binding IgE and IgD
- Recognize specific antigens (allergens or parasites)
- Mast cells, eosinophils, and basophils often work together.
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Description
Test your knowledge on various aspects of allergic reactions and immune responses. This quiz covers key concepts such as the immediate and delayed responses, IgE antibodies, and the role of specific cells in hypersensitivity reactions. Perfect for students studying immunology or related fields.
