Immunology: Type IV Hypersensitivity

<p>Dendritic cells</p> Signup and view all the answers

<p>Destruction of infected cells</p> Signup and view all the answers

<p>Increased vascular permeability</p> Signup and view all the answers

<p>Delayed onset</p> Signup and view all the answers

<p>Release of granule proteins</p> Signup and view all the answers

<p>Activation of the complement system</p> Signup and view all the answers

<p>TNF-alpha</p> Signup and view all the answers

<p>All of the above</p> Signup and view all the answers

<p>Both b and c</p> Signup and view all the answers

<p>IgG</p> Signup and view all the answers

<p>Anaphylaxis with a rapid drop in blood pressure</p> Signup and view all the answers

<p>Mast cells release histamine and other mediators upon activation by IgE</p> Signup and view all the answers

<p>All of the above</p> Signup and view all the answers

<p>Congestion</p> Signup and view all the answers

<p>Histamine</p> Signup and view all the answers

<p>Rapid vasodilation</p> Signup and view all the answers

<p>Bronchial gland hyperplasia</p> Signup and view all the answers

<p>Histamine release</p> Signup and view all the answers

<p>Eosinophilic inflammation</p> Signup and view all the answers

<p>Fluid leakage into tissues</p> Signup and view all the answers

<p>Mast cells</p> Signup and view all the answers

<p>It develops within minutes after challenge.</p> Signup and view all the answers

<p>Inflammatory infiltrate rich in eosinophils</p> Signup and view all the answers

<p>Inflammatory infiltrate rich in eosinophils, neutrophils, and T cells.</p> Signup and view all the answers

<p>2 to 24 hours later.</p> Signup and view all the answers

<p>Delayed influx of eosinophils</p> Signup and view all the answers

<p>Cytokines and chemokines</p> Signup and view all the answers

<p>The immediate response is characterized by a quick vascular reaction.</p> Signup and view all the answers

<p>Eosinophils and neutrophils</p> Signup and view all the answers

<p>Type I hypersensitivity</p> Signup and view all the answers

<p>Characterized by delayed-onset symptoms</p> Signup and view all the answers

<p>Anaphylaxis</p> Signup and view all the answers

<p>To bind to mast cells and initiate degranulation</p> Signup and view all the answers

<p>They present allergens to T helper cells</p> Signup and view all the answers

<p>They produce cytokines that promote IgE production</p> Signup and view all the answers

<p>All of the above</p> Signup and view all the answers

<p>Exocytosis of granules</p> Signup and view all the answers

<p>Triggered by non-immune stimuli</p> Signup and view all the answers

<p>Myasthenia gravis</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>IgE binds to FcεRI receptors on mast cells.</p> Signup and view all the answers

<p>CD4+ T cells recognize and respond to allergens by binding to IgE on the surface of mast cells, leading to cross-linking and activation of mast cells, which then release mediators that induce chronic inflammation.</p> Signup and view all the answers

<p>Th2 cells stimulate the production of IgE antibodies, which bind to mast cells.</p> Signup and view all the answers

<p>The activation of the complement system leads to inflammation and tissue injury.</p> Signup and view all the answers

<p>Eosinophils contribute to the pathogenesis of allergic reactions by releasing granule proteins that damage tissues and exacerbate inflammation. Their presence in bronchial walls is a hallmark of allergic reactions and contributes to the development of airway obstruction.</p> Signup and view all the answers

<p>Fc receptors on CD8+ T cells recognize and bind to IgE, allowing CD8+ T cells to recognize and respond to allergens, leading to the release of cytotoxic granules and cell death.</p> Signup and view all the answers

<p>Mast cells release histamine and other mediators, leading to allergic symptoms.</p> Signup and view all the answers

<p>Eosinophils play a role in the late-phase reaction, contributing to chronic inflammation.</p> Signup and view all the answers

<p>The immediate phase reaction is characterized by the rapid release of mediators from mast cells, leading to symptoms such as edema and vasodilation. The late-phase reaction, which develops hours after allergen exposure, is characterized by the infiltration of eosinophils and the release of pro-inflammatory cytokines, leading to chronic inflammation.</p> Signup and view all the answers

<p>Mast cells contribute to the development of chronic inflammation by releasing mediators that attract and activate immune cells, such as eosinophils and T cells, leading to the production of pro-inflammatory cytokines and the perpetuation of inflammation.</p> Signup and view all the answers

<p>Immediate hypersensitivity reactions are mediated by IgE and mast cells, while delayed hypersensitivity reactions are mediated by T cells and macrophages.</p> Signup and view all the answers

<p>IgE plays a crucial role in the development of immediate hypersensitivity reactions by binding to allergens and facilitating the activation of mast cells and basophils, leading to the release of mediators and the development of allergic symptoms.</p> Signup and view all the answers

<p>CD4+ T cells and eosinophils interact in the development of chronic inflammation by CD4+ T cells recognizing and responding to allergens, leading to the activation of eosinophils, which then release granule proteins that exacerbate inflammation.</p> Signup and view all the answers

<p>Type I hypersensitivity reactions are characterized by the rapid release of mediators from mast cells and basophils in response to allergens, leading to immediate symptoms. Type IV hypersensitivity reactions, on the other hand, are characterized by the activation of T cells and the release of cytokines, leading to delayed symptoms.</p> Signup and view all the answers

<p>Antibodies opsonize circulating cells, enhancing their targeting for phagocytosis.</p> Signup and view all the answers

<p>Repeated exposure can lead to heightened sensitivity and an exaggerated immune response.</p> Signup and view all the answers

<p>Complement-mediated destruction effectively helps eliminate pathogens through cell lysis and inflammation.</p> Signup and view all the answers

<p>Hypersensitivity involves an overreaction to harmless substances, leading to tissue damage.</p> Signup and view all the answers

<p>Circulating immune cells, such as red blood cells and platelets, are targeted in the allergic response.</p> Signup and view all the answers

<p>Inflammation results from the immune system's response to allergens, causing various symptoms.</p> Signup and view all the answers

<p>Sensitization primes the immune system, making it more likely to react strongly upon re-exposure.</p> Signup and view all the answers

<p>The immune response can shift to become increasingly robust and potentially harmful with repeated exposures.</p> Signup and view all the answers

<p>IgE binds to the high-affinity IgE receptor (FcεRI) on the surface of mast cells. When a multivalent allergen binds to the IgE molecules attached to FcεRI, it cross-links the receptors, triggering mast cell degranulation. This release of pre-formed mediators like histamine, leukotrienes, and prostaglandins, along with newly synthesized cytokines, is responsible for the immediate symptoms of an allergic reaction.</p> Signup and view all the answers

<p>Allergens can enter the body through various routes: inhalation (e.g., pollen, dust mites), ingestion (e.g., peanuts, shellfish), injection (e.g., bee venom), or skin contact (e.g., latex, poison ivy). These allergens can be normal molecules, components of microorganisms, or exogenous substances like drugs or their metabolites. In some cases, antibodies to microbial or other antigens can cross-react with allergens, leading to sensitization.</p> Signup and view all the answers

<p>Cross-reactivity occurs when antibodies or T cells specific for one allergen can also recognize and react with a different, structurally similar allergen. This can lead to sensitization to multiple allergens, even if exposure to a particular allergen has been limited. For example, someone with a peanut allergy may also react to other legumes like soybeans or lentils due to cross-reactivity between the allergens present in these foods.</p> Signup and view all the answers

<p>Eosinophils are recruited to the site of inflammation during the late-phase reaction of immediate hypersensitivity. They release a variety of mediators, including enzymes, cytokines, and chemokines, that contribute to tissue damage, remodeling, and chronic inflammation. This process can contribute to persistent symptoms and the development of chronic allergic conditions like asthma.</p> Signup and view all the answers

<p>Immediate hypersensitivity reactions can range from mild symptoms like sneezing, itching, and runny nose to severe reactions like anaphylaxis, characterized by life-threatening airway obstruction, hypotension, and shock. The severity of the response depends on factors such as the amount of allergen exposure, the individual's sensitivity, and the location of the allergic reaction. Systemic reactions involving multiple organ systems pose the greatest risk.</p> Signup and view all the answers

<p>The immediate reaction occurs within minutes of allergen exposure and is characterized by the rapid release of pre-formed mediators from mast cells, such as histamine, leukotrienes, and prostaglandins. The late-phase reaction occurs several hours later and involves the recruitment of inflammatory cells, including eosinophils and T cells, along with the release of cytokines and chemokines. While both phases contribute to the overall allergic response, the immediate reaction is typically responsible for the acute symptoms, while the late-phase reaction contributes to the development of chronic inflammation.</p> Signup and view all the answers

<p>Atopic allergy is characterized by a genetic predisposition to develop IgE-mediated allergic reactions, often involving multiple allergens and a history of eczema, asthma, or hay fever. Non-atopic allergy, in contrast, is not associated with a familial history of allergies and typically involves a single allergen, often triggered by specific environmental exposures. Examples of atopic allergies include pollen allergies, food allergies, and pet allergies. Non-atopic allergies can include reactions to latex, certain medications, or industrial chemicals.</p> Signup and view all the answers

<p>CD4+ T cells play a critical role in the development and persistence of allergic reactions. Following allergen presentation by antigen-presenting cells (APCs), they differentiate into Th2 cells. Th2 cells release cytokines like IL-4, IL-5, and IL-13, which promote IgE production by B cells, eosinophil differentiation and recruitment, and tissue remodeling. This cascade of events contributes to the development of chronic inflammation and the persistent symptoms of allergic conditions.</p> Signup and view all the answers

<p>In Type III hypersensitivity, antigen-antibody complexes form in the circulation. These complexes can then deposit in blood vessel walls, triggering complement activation. This leads to the release of inflammatory mediators, such as anaphylatoxins (C3a and C5a) and chemotactic factors, which attract neutrophils and other inflammatory cells. These cells release additional inflammatory mediators, resulting in tissue damage and inflammation.</p> Signup and view all the answers

<p>In delayed-type hypersensitivity (Type IV), CD4+ T cells release cytokines, primarily TNF-α, IFN-γ, and IL-2. These cytokines contribute to tissue injury by recruiting and activating macrophages, which release destructive enzymes and reactive oxygen species. They also promote the expression of adhesion molecules on vascular endothelium, facilitating further leukocyte infiltration and amplification of the inflammatory response.</p> Signup and view all the answers

<p>CD8+ T cells, also known as cytotoxic T lymphocytes, are directly involved in tissue injury in Type IV hypersensitivity. They recognize and kill cells displaying specific antigens on their surface. This process is mediated by the release of cytotoxic substances, such as perforin and granzyme, which induce apoptosis in the target cell. This cytotoxic activity can contribute to the development of tissue damage and inflammation characteristic of Type IV hypersensitivity.</p> Signup and view all the answers

<p>Type IV hypersensitivity, unlike Type III, is a T cell-mediated response. It involves the sensitization of T cells to specific antigens. The primary mechanism of tissue injury in Type IV is cell-mediated cytotoxicity, primarily by CD8+ T cells, and cytokine-mediated inflammation, driven by CD4+ T cells. Type III hypersensitivity, in contrast, is antibody-mediated, relying on the formation of antigen-antibody complexes that trigger complement activation and subsequent inflammation. The immune dysregulation in Type IV involves the inappropriate activation of T cells against self-antigens or foreign antigens, leading to direct cell killing and cytokine-mediated inflammation, whereas in Type III, the immune dysregulation is related to the overproduction of antibodies and the formation of immune complexes.</p> Signup and view all the answers

<p>The deposition of antigen-antibody complexes in blood vessels, a hallmark of Type III hypersensitivity, can contribute to the development of autoimmune diseases by triggering chronic inflammation and tissue damage. These complexes activate the complement system, leading to the release of inflammatory mediators that attract immune cells, such as neutrophils, to the site of deposition. These cells can then release destructive enzymes and reactive oxygen species, damaging surrounding tissues. For instance, in systemic lupus erythematosus (SLE), a chronic autoimmune disease, autoantibodies form against nuclear antigens. These immune complexes deposit in various tissues, including the kidneys, joints, and skin, causing inflammation and tissue damage, leading to the characteristic symptoms of the disease.</p> Signup and view all the answers

<p>Type IV hypersensitivity is a T cell-mediated response, characterized by delayed-type hypersensitivity. It involves direct cell cytotoxicity by CD8+ T cells and cytokine-mediated inflammation by CD4+ T cells. Type I hypersensitivity, on the other hand, is an immediate hypersensitivity reaction mediated by IgE antibodies. It involves the cross-linking of IgE on mast cells, leading to the release of pre-formed mediators, such as histamine, and the subsequent recruitment of other inflammatory cells. While Type IV involves direct T cell-mediated killing and cytokine-driven inflammation, Type I relies on the rapid release of mediators from mast cells and the subsequent cascade of inflammatory events.</p> Signup and view all the answers

<p>I</p> Signup and view all the answers

<p>cross-linking</p> Signup and view all the answers

<p>chronic</p> Signup and view all the answers

<p>Fc</p> Signup and view all the answers

<p>hours</p> Signup and view all the answers

<p>eosinophils</p> Signup and view all the answers

<p>mast</p> Signup and view all the answers

<p>histamine</p> Signup and view all the answers

<p>prostaglandin D2</p> Signup and view all the answers

<p>bronchoconstriction</p> Signup and view all the answers

<p>cyclooxygenase</p> Signup and view all the answers

<p>congestion</p> Signup and view all the answers

<p>anaphylactic</p> Signup and view all the answers

<p>mucous</p> Signup and view all the answers

<p>dendritic cells</p> Signup and view all the answers

<p>plasma</p> Signup and view all the answers

<p>hypersensitivity</p> Signup and view all the answers

<p>proteins</p> Signup and view all the answers

<p>receptors</p> Signup and view all the answers

<p>inflammation</p> Signup and view all the answers

<p>Fc</p> Signup and view all the answers

<p>complement</p> Signup and view all the answers

<p>immediate</p> Signup and view all the answers

<p>late</p> Signup and view all the answers

<p>complement</p> Signup and view all the answers

<p>initial</p> Signup and view all the answers

<p>histamine</p> Signup and view all the answers

<p>mast</p> Signup and view all the answers

<p>spasmogenic</p> Signup and view all the answers

<p>facilitate</p> Signup and view all the answers

<p>chemokines</p> Signup and view all the answers

<p>bronchial</p> Signup and view all the answers

<p>systemic</p> Signup and view all the answers

<p>inflammatory</p> Signup and view all the answers

<p>vascular</p> Signup and view all the answers

<p>regulate</p> Signup and view all the answers

<p>Hypersensitivity = An overactive immune response Atopy = A type of hypersensitivity reaction that involves IgE antibodies Autoimmunity = The immune system's ability to distinguish between self and non-self Immune complex-mediated hypersensitivity = A type of hypersensitivity reaction that involves the formation of immune complexes</p> Signup and view all the answers

<p>Mast cells = Release histamine and other mediators CD4+ T cells = Induce chronic inflammation in response to an allergen Dendritic cells = Present antigens to T cells Eosinophils = Release anti-inflammatory mediators</p> Signup and view all the answers

<p>Histamine = Increased vascular permeability and smooth muscle contraction Leukotrienes = Bronchospasm, vascular permeability, and mucus secretion Prostaglandins = Vasodilation, pain, and fever Cytokines = Recruitment and activation of inflammatory cells</p> Signup and view all the answers

<p>Anaphylaxis = A severe, systemic allergic reaction Atopy = A type of hypersensitivity reaction that involves IgE antibodies Immune tolerance = The immune system's ability to distinguish between self and non-self Inflammation = A local immune response to tissue damage or infection</p> Signup and view all the answers

<p>Histamine = Causes smooth muscle contraction and increased vascular permeability IgE = Triggers the release of histamine and other mediators from mast cells Leukotrienes = Causes bronchial constriction and increased mucus production Prostaglandins = Causes fever and pain</p> Signup and view all the answers

<p>Type I hypersensitivity = Involve IgE antibodies and immediate symptoms Type II hypersensitivity = Involve IgG or IgM antibodies and complement activation Type III hypersensitivity = Involve immune complexes and inflammation Type IV hypersensitivity = Involve T cell-mediated delayed reactions</p> Signup and view all the answers

<p>Acute inflammation = A local immune response to tissue damage or infection Chronic inflammation = A prolonged immune response to persistent infection or tissue damage Immune tolerance = The immune system's ability to distinguish between self and non-self Immunologic memory = The ability of the immune system to remember specific antigens</p> Signup and view all the answers

<p>Th2 cells = Produce cytokines that promote IgE production Dendritic cells = Present antigens to T cells Eosinophils = Release granules that cause tissue damage Mast cells = Release histamine and other mediators</p> Signup and view all the answers

<p>Allergen = A substance that triggers an allergic response Antigen = A substance that triggers an immune response Hapten = A small molecule that can trigger an immune response when bound to a carrier protein Immunogen = A substance that triggers an adaptive immune response</p> Signup and view all the answers

<p>Vasodilation, congestion, and edema = Immediate reaction Inflammation rich in eosinophils, neutrophils, and T cells = Late-phase reaction Release of mediators from mast cells = Immediate reaction Systemic reaction = Late-phase reaction</p> Signup and view all the answers

<p>Histamine = Causes smooth muscle contraction and increased vascular permeability Eosinophils = Rich in inflammatory infiltrate IgE = Binds to allergens and triggers mast cell degranulation T cells = Presents antigens to immune cells</p> Signup and view all the answers

<p>Mast cells = Release histamine and other mediators Eosinophils = Rich in inflammatory infiltrate T cells = Presents antigens to immune cells Neutrophils = Part of inflammatory infiltrate</p> Signup and view all the answers

<p>Antibody-mediated = Type II hypersensitivity Immune complex-mediated = Type III hypersensitivity Immediate hypersensitivity = Type I hypersensitivity Delayed-type hypersensitivity = Type IV hypersensitivity</p> Signup and view all the answers

<p>Within minutes = Immediate reaction 2 to 24 hours later = Late-phase reaction Hours after exposure = Delayed-type hypersensitivity Days after exposure = Late-phase reaction</p> Signup and view all the answers

<p>Vasodilation = Immediate reaction Congestion = Immediate reaction Edema = Immediate reaction Inflammation rich in eosinophils, neutrophils, and T cells = Late-phase reaction</p> Signup and view all the answers

<p>Mast cells = Tissue-bound Eosinophils = Inflammatory infiltrate T cells = Lymphoid organs Neutrophils = Bloodstream</p> Signup and view all the answers

<p>Upper airway obstruction = Systemic reaction Bronchial changes = Asthma Edema = Local reaction Inflammation = Late-phase reaction</p> Signup and view all the answers

<p>Vasoactive amines = Cause central dysfunction: Anaphodies can also cause central dysfunction Cytokines = Produce functional decrements without cell or tissue injury Lipid mediators = Bind to and activate or inhibit receptors on the surface of cells, producing functional decrements = Bind to and deplete essential molecules, producing functional decrements with cell or tissue injury</p> Signup and view all the answers

<p>IgE antibodies = Type I hypersensitivity Immune complexes = Type III hypersensitivity IgG or IgM antibodies = Type II hypersensitivity T cell-mediated = Type IV hypersensitivity</p> Signup and view all the answers

<p>Mast cells = Release histamine and other mediators Eosinophils = Present antigens to T cells Dendritic cells = Activate T cells Th2 cells = Produce cytokines</p> Signup and view all the answers

<p>Smooth muscle contraction = Immediate hypersensitivity reaction Increased vascular permeability = Late-phase reaction Eosinophil infiltration = Type I hypersensitivity Upper airway obstruction = Systemic immediate hypersensitivity reaction</p> Signup and view all the answers

<p>Histamine = Causes smooth muscle contraction Leukotrienes = Increases vascular permeability Prostaglandins = Causes smooth muscle relaxation Cytokines = Recruits eosinophils</p> Signup and view all the answers

<p>IgE-mediated = Type I hypersensitivity Immune complex-mediated = Type III hypersensitivity Antibody-mediated = Type II hypersensitivity T cell-mediated = Type IV hypersensitivity</p> Signup and view all the answers

<p>Dendritic cells = Present antigens to T cells Mast cells = Release histamine and other mediators Eosinophils = Present antigens to B cells Th2 cells = Produce cytokines</p> Signup and view all the answers

<p>Type I hypersensitivity = Immediate reaction Type IV hypersensitivity = Delayed reaction Type II hypersensitivity = Antibody-mediated reaction Type III hypersensitivity = Immune complex-mediated reaction</p> Signup and view all the answers

<p>IL-4 = Stimulates B cell differentiation into IgE-producing plasma cells IL-5 = Activates eosinophils, contributing to inflammation IL-13 = Enhances mucus production and airway hyperresponsiveness TNF-alpha = Induces inflammation and tissue damage</p> Signup and view all the answers

<p>Sensitization = Initial exposure to an allergen that primes the immune system Degranulation = Release of preformed mediators from mast cells Late-phase reaction = Delayed inflammatory response occurring hours after allergen exposure Atopic = Genetic predisposition to develop allergies</p> Signup and view all the answers

<p>Histamine = Causes vasodilation, increased vascular permeability, and bronchoconstriction Leukotrienes = Contribute to bronchoconstriction, mucus production, and vascular permeability Prostaglandins = Induce vasodilation, pain, and inflammation Cytokines = Regulate the immune response and contribute to inflammation</p> Signup and view all the answers

<p>Anaphylaxis = Systemic, life-threatening reaction characterized by airway obstruction, hypotension, and shock Asthma = Chronic inflammatory airway disease characterized by bronchospasm, wheezing, and mucus production Atopic dermatitis = Chronic inflammatory skin condition characterized by itching, redness, and dryness Hay fever = Allergic rhinitis characterized by sneezing, runny nose, and itchy eyes</p> Signup and view all the answers

<p>Mast cells = Release mediators upon degranulation, contributing to the immediate reaction Eosinophils = Infiltrate the site of inflammation and contribute to tissue damage B cells = Produce IgE antibodies in response to allergen exposure T cells = Regulate the immune response and contribute to the development of allergies</p> Signup and view all the answers

<p>Sensitization = Initial exposure to an allergen Degranulation = Release of mediators from mast cells Late-phase reaction = Delayed inflammatory response Production of IgE antibodies = B cell differentiation into IgE-producing plasma cells</p> Signup and view all the answers

<p>Type I = Immediate, IgE-mediated Type II = Antibody-mediated, cytotoxic Type III = Immune complex-mediated Type IV = Cell-mediated, delayed</p> Signup and view all the answers

<p>Asthma = Dust mites, pollen, pet dander Atopic dermatitis = Food allergens, environmental allergens Anaphylaxis = Insect stings, medications, food allergens Hay fever = Pollen, mold, dust mites</p> Signup and view all the answers