Suzy, a college student who is 21 years old, has suffered from many environmenta
ID: 21596 • Letter: S
Question
Suzy, a college student who is 21 years old, has suffered from many environmental and food allergies as well as allergic asthma since grade school. She had taken allergy injections and numerous medications, but her asthma was still problematic. Her doctor suggested she try a new type of prescription medication given by injection called Xolair. Xolair works by binding to IgE antibodies.(a) Describe how an allergic response occurs, including the sensitization stage, and the role of IgE antibodies in this process.
(b) Briefly describe what allergic asthma is, and how Xolair could reduce the incidence of allergic asthma attacks.
(c) Suzy also found that she could safely eat many of the foods to which she had been allergic after about 6 months of Xolair shots. Explain why this side-benefit occurred.
Explanation / Answer
a)Based upon the observation that allergic responses typically affect the skin, gut, and respiratory tract, the major sites of parasitic invasion, it is thought that IgE evolved as a defence against parasitic infestation. Helminths stimulate a vigorous IgE production, including parasite-specific IgE antibody. However, another hypothesis for the beneficial function of IgE antibodies is that they play a key role in very early recognition of foreign material ("gate keeper function") or a general potentiation of the immune system response by improved antigen presentation. Actually, allergy triggered by IgE may be considered a beneficial function to the host; the typical allergic reactions of mucus secretion, sneezing, itching, coughing, bronchoconstriction, tear production, inflammation, vomiting and diarrhoea are all mechanisms that expel allergenic proteins from the body. The immune reponse in allergy begins with sensitization. When, for example, house dust mite or pollen allergens are inhaled, antigen presenting cells such as Langerhans cells in the epithelium lining the airways of the lungs and nose, internalise, process and then express these allergens on their cell surface. The allergens are then presented to other cells involved in the immune response, particularly T-lymphocytes. Through a series of specific cell interactions B-lymphocytes are transformed into antibody secretory cells - plasma cells. In the allergic response, the plasma cell produces IgE-antibodies, which, like antibodies of other immunoglobulin isotypes, are capable of binding a specific allergen via its Fab portion. Different allergens stimulate the production of corresponding allergen-specific IgE antibodies. Once formed and released into the circulation, IgE binds, through its Fc portion, to high affinity receptors on mast cells, leaving its allergen specific receptor site available for future interaction with allergen. Other cells known to express high-affinity receptors for IgE include basophils, Langerhans cells and activated monocytes. Production of allergen specific IgE-antibodies completes the immune response known as sensitization. b)the Xolair dosage used to prevent asthma attacks is based on several factors, such as your weight and the results of certain lab tests. This article takes a closer look at the factors that can affect Xolair dosing. Xolair Drug Information Xolair Drug Interactions There are no known drug interactions with Xolair. But as this eMedTV page explains, you should talk with your doctor about any possible Xolair drug interactions that may apply to you -- since there may be interactions that aren't known at this time. Xolair for Asthma Your doctor may prescribe Xolair for asthma if your allergic asthma is not controlled by inhaled steroids. This eMedTV resource describes how Xolair works and explains what you should discuss with your healthcare provider before using this medication. Xolair Injections Xolair is a prescription drug used to prevent asthma attacks in people with allergic asthma. As this eMedTV page explains, the medicine comes in injectable form. Xolair injections are typically given every two to four weeks by your healthcare provider. Xolair Uses As this eMedTV page explains, Xolair is used to prevent allergic asthma attacks that are not adequately controlled by inhaled corticosteroids. This page also covers Xolair uses in children and lists off-label uses (like preventing seasonal allergies). Xolair Warnings and Precautions Some people who take Xolair may experience an immediate worsening of asthma symptoms. This eMedTV page covers other Xolair warnings and precautions, such as the safety of taking Xolair while nursing or pregnant and people who should not take the drug. Xolaire Xolair is a medication used for allergic asthma given to people who have not responded to inhaled steroids. This eMedTV page offers an in-depth look at Xolair and its uses, effects, and side effects. Xolaire is a common misspelling of Xolair. Xopanex Xopenex is a prescription medicine approved for the treatment or prevention of airway spasms. This eMedTV page briefly describes the effects of Xopenex and provides a link to more detailed information. Xopinex is a common misspelling of Xopenex. Xopenex Xopenex is a prescription drug that is approved to treat asthma or other similar respiratory conditions. This eMedTV article describes the other conditions the medication can treat, explains how it works, and highlights potential side effects. c)Xolair (Omalizumab) is a recombinant DNA-derived humanized IgG1? monoclonal antibody that selectively binds to human immunoglobulin E (IgE). The antibody has a molecular weight of approximately 149 kilodaltons. Xolair (omalizumab) is produced by a Chinese hamster ovary cell suspension culture in a nutrient medium containing the antibiotic gentamicin. Gentamicin is not detectable in the final product. Xolair (omalizumab) is a sterile, white, preservative-free, lyophilized powder contained in a single-use vial that is reconstituted with Sterile Water for Injection (SWFI), USP, and administered as a subcutaneous (SC) injection. A Xolair vial contains 202.5 mg of Omalizumab, 145.5 mg sucrose, 2.8 mg L-histidine hydrochloride monohydrate, 1.8 mg L-histidine, and 0.5 mg polysorbate 20, and is designed to deliver 150 mg of Omalizumab in 1.2 mL after reconstitution with 1.4 mL SWFI, USP.
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