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MSU MMG 451 - Homework 4.2

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Learning objective 4.2.1: Use tables, graphs and drawings to characterize the causes and consequences of hypersensitivity reactions.MMG 451 – Spring 2021Unit 4 – Tolerance, Memory, and Unwanted Immune ResponsesHomework 4.2 – Due 04-09-20 before 3:00 PMLearning objective 4.2.1: Use tables, graphs and drawings to characterize the causes and consequences of hypersensitivity reactions. Read the introduction of Chapter 14, section 14-1, and Figure 14.2 in order to:- Make a table to compare the four different types of hypersensitivity reactions. In the table, indicate the immune mediator (e.g. IgE) and the effector mechanism for responsible for each type of hypersensitivity and the general timing of associated symptoms.Type I Type II Type III Type IVImmune mediator IgE IgG IgG effector T-cellEffectormechanismallergenschemicalmodificationforeign protein foreign protein- Fill in the following sentence: Allergies are classified as a type _I_ hypersensitivity reaction.Define atopic – indicates a form of allergy in which a hypersensitivity reaction such as dermatitis or asthma may occur in a part of the body not in contact with the allergen.Read section 9-13 in order to:- Describe the role of IgE-mediated immune responses in the human body. o IgE provides a mechanism for the rapid ejection of parasites and other pathogens from the body. IgE does not function by binding to antigens as a soluble antibody but is used as a cell-surface receptor for the antigen. The Fc region of IgE is bound by an Fc receptor, FcERI, on mast cells, basophils, and activated eosinophils. When a pathogen binds to the IgE on a mast cell and cross-links two or more FcERI molecules, the cell secretes active mediators that act on smooth muscle to cause violent reactions (coughing, vomiting, diarrhea) that forcibly eject pathogens from the respiratory and gastrointestinal tracts. IgE is the anti- body isotype that works in the connective tissue (mucosal surfaces specifically) and is specialized in ejecting toxicsubstances and pathogens.- Draw a picture of an inactive mast cell that has been “sensitized” by IgE binding. Then add an antigen to the picture to demonstrate how the mast cell becomes activated.- Describe what happens once the mast cell is activated i.e. what is released from the mast cell. o To activate the cell, the antigen must cross-link at least two IgE molecules and their associated receptors, which means that the antigen must have at least two topographically separate epitopes recognized by the cell bound IgE. Cross-linking of FcERI generates the signal that initiates the release of the mast-cell granules. After degranulation, the mast cell synthesizes and packages a newset of granules. Associated cells of the immune system (mast, basophils, etc.) move out of the bloodstream and into tissues which causes a local accumulation of fluid, and the swelling, reddening, and pain that characterize inflammation. Inflammation in response to an infection is beneficial because it recruits cells and proteins required for host defense into the sites of infection. Read section 14-4 in order to:Define hygiene hypothesis – hypothesis advanced to explain the increasing incidence over the past 50 years ofhypersensitivity and autoimmune diseases in developed countries. It is proposed that the increase has occurred because widespread hygiene, vaccination, and antibiotic therapy have prevented children’s immune systems from becoming used to dealing appropriately with either natural infections or innocuous environmentalantigens. - Propose an observation that would support the hygiene hypothesis by filling in the following sentence:o People who have fewer _____vaccines_____ have more _____associated disease_____.Look at Figure 16.1 in order to:- Recognize autoimmune diseases as different types of hypersensitivity reactions.- Choose one disease from each of the types of hypersensitivity (type II, type III, type IV) and make a different graph for each to compare healthy individuals vs. patients with the disease. For the y-axis label, choose a measurement that reflects a major immune component responsible for the hypersensitivity. (hint: refer to the table made for section 14-1 reading)Type II: hypoglycemia Type III: subacute bacterial endocarditis Type IV: Type 1 diabetesTissue tissue tissueDamage damage damageHealthy w/ disease healthy w/ disease healthy w/ disease Read section 16-5 and study Figure 16.13 and Figure 16.14 in order to:- Classify the autoantibodies as agonistic or antagonistic in patients with Graves’ disease vs. the patientswith myasthenia gravis.o Graves’ disease: agonist (antigen is thyroid stimulating hormone receptor); (consequence is hypothyroidism); (target cell is thyroid epithelial cell)o Myasthenia gravis: antagonist (antigen is acetylcholine receptor); (consequence is progressive muscle weakness); (target cell is muscle

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