New version page

Virginia Tech BIOL 4704 - Test 4 Outline

Documents in this Course
Load more
Upgrade to remove ads

This preview shows page 1-2-14-15-29-30 out of 30 pages.

Save
View Full Document
Premium Document
Do you want full access? Go Premium and unlock all 30 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 30 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 30 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 30 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 30 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 30 pages.
Access to all documents
Download any document
Ad free experience

Upgrade to remove ads
Unformatted text preview:

Test 4 Outline Joseph SuslikHypersensitivities-Immune system over-reacts following contact with otherwise harmless foreign substancesand cause allergic disease-The immune system is not infallible, it can malfunction-Four major types of malfunction, depending on the mechanism used to cause tissue damage-Type I: Anaphylactic (immediate) hypersensitivity (Commonly called Allergy)-Type II: Antibody-dependent cytotoxic hypersensitivity-Type III: Immune complex mediated-Type IV: Cell-mediated (delayed type) hypersensitivity -First 3 types are a result of Ab interactions, type 4 is based on TH1 cells and activated M sϕ-Type I allergy requires at least three components-a disease-eliciting allergen -a transferable serum factor that discriminates allergic patients from health individuals (IgE)-a tissue component that is present in all individuals (mast cells) -Hypersensitivity states-Acquired immune response-The mechanism is identical to specific responses to infectious agents-Responses are considered deleterious only because they are inappropriate or cause tissue damage Examples:-Allergy: responses to innocuous Ags-Autoimmune diseases: responses to self-Ags-Graft rejection: responses to transplanted Ags-Hypersensitivity is the increased state of reactivity-Allergy is an “altered” response caused by an allergen-Immunization = sensitization-Booster = shocking/activation dose-Immediate hypersensitivity is the rxns that appear quickly after 2nd exposure to allergen; 2-4 hours after immediate rxn, a late phase rxn develops (recruitment of eosinophils and TH2 cells)-Immunity is the prophylactic state, reverse state is anaphylaxis-Systemic anaphylaxis can lead to anaphylactic shock-The genetic tendency to develop allergies against nonparasitic allergens and have one or more allergies is called atopy-Delayed hypersensitivity is when the sensitivity appears much later-Hyposensitivity is the opposite of hypersensitivity, it is achieved by desensitization -Most common type of antibody-mediated hypersensitivities are allergic reactions-Hay fever, asthma, and hives-Produced when the immune system responds to a false alarm-Normally harmless substance – grass pollen or house dust – perceived as a threat and is attacked-Allergy overreactions occur usually within minutes of a second exposure with an antigen (or allergen)-Mediated by antibody, mast cells, basophils, eosinophils, and the products produced by these cells-The hypersensitivity only occurs in individuals that are immunologically sensitized to the substance-Common US allergies-Allergic rhinitis (hay fever): affects 22% of US population, common causative agents are plant pollens, animal dander, and dust mite feces-Inflammation of the mucous membrane lining the nose, becomes swollen, leading to partial or complete obstruction of air-flow with excess local mucus production-Asthma: affects over 20 million US residents, same causative agents as rhinitis-Atopic dermatitis: reactions like eczema and urticarial (hives), commonly caused by insect venom-A chronic skin disease in which the skin becomes extremely itchy and inflamed; causing redness, swelling, cracking, weeping, crusting, and scaling-Its multifactorial pathogenesis-Allergic gastroenteropathy (food allergies): common causative agents are peanuts and shellfish-Anaphylaxis (acute systemic allergic reaction) caused by insect venom, antibiotics, foods, etc. -Generalized release of histamine and other inflammatory mediators following systemic induction of mast-cell degranulation by allergen-Causes bronchospasm, cardiovascular collapse, and death-Inhaled allergens are pollen, mites/mites’ feces (20% of US pop) = asthma, rhinitis, conjunctivitis -Ingested allergens are eggs, fish, milk, peanuts, shellfish, wheat = diarrhea, urticarial, angioedema, vomiting-Cutaneous, subcutaneous, intravenous allergens are drugs, insect stings, serums, venoms, and latex (1-6% of US pop.) = atopic dermatitis, systemic anaphylaxis-Allergic: you have a clinically evident reaction to allergens, which is reflected by acquired immune responses predominated by the presence of allergen-specific IgE, together with mast cell and eosinophil recruitment and activation. CD4+ T cells producing a TH2 profile of cytokines (IL-4, IL-5, IL-9, and IL-13), which are central to the development of allergic responses-APC allergen presentation to TH2 cells is greater than B cells-TH2 cell-derived IL-4 & IL-13 promotes isotype switching to IgEIL-5 promotes eosinophil recruitment-Magnitude and duration of IgE responses are determined by cross-regulation between antagonistic IL-4 and IL-10 and TH1 cell derived IFN-γ -Mast cells produce IL-4, IL-5, TNF- , GM-CSF, and chemokinesα-CD4+ TH1 cells can regulate the IgE response-Related to immunoglobulin E (IgE)-Each Ab is specific and produced in response to an earlier contact with the antigen, an antigen that stimulates high levels of IgE (sensitization)-Ex: One Ab reacts against oak pollen, another against ragweed.-Normal role of IgE is unknown; scientists suspect that it developed as a defense against infection by parasitic worms-First time an allergy-prone person exposed to an allergen, they make large amount of corresponding IgE antibody-These IgE molecules attach to the surface of mast cells (in tissues) or basophils (in circulation)-Mast cells are plentiful in the lungs, skin, tongue, and linings of the nose and intestinal tract-When an IgE Ab sitting on a mast cell or basophil encounters its specific allergen, the IgE antibody signals the mast cell or basophil to release the powerful chemicals stored within its granules-Chemicals include histamine, heparin, and substances that activate blood platelets and attract secondary cells such as eosinophils and neutrophils-Activated mast cell or basophil also synthesizes new mediators, including prostaglandins, leukotrienes, and cytokines, on the spot-These chemical mediators cause the symptoms of allergy: wheezing, sneezing, runny nose, water eyes, and itching-Can also produce anaphylactic shock, a life-threatening allergic reaction char. by swelling of body tissues (throat) and a sudden drop in blood pressure-Type IV Delayed-type hypersensitivity begins after a latent period of several hours and reaches a peak 48-72 hours later-Dependent on activity of T cells rather than antibody-When the Ag reacts with the specific T cells, they are activated to secrete a number


View Full Document
Download Test 4 Outline
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Test 4 Outline and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Test 4 Outline 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?