|The Allergy Center|
Allergy = Hypersensitivity
This website was developed for a reader who wants to learn more about immune mediated disease. We use the term Allergy according to the original definition included all immune mediated disease. There are different types of allergy. The immediate or type 1 hypersensitivity is easily recognized because it involves quick and dramatic symptoms. Common problems related to immediate patterns of allergy include hay fever, asthma, rhinitis, otitis media, atopic dermatitis, urticaria, and anaphylaxis. Hay fever is the most common expression of type 1 allergy and is a prototype of immediate hypersensitivity. Hay fever is a reaction to airborne plant pollens in the eyes, nose and throat. Allergy tests are positive to the allergenic pollens, antihistamines help and allergy shots can reduce the reactivity over time. Delayed patterns of allergy are not so obvious and generally go unrecognized. Allergy skin tests do not show this problem nor do IgE serum antibody tests
Allergy ConceptsThe original concept of allergy included all immune-mediated disease and the term allergy was interchangeable with the term "hypersensitivity." Allergy can be thought of as hypersensitivity disorders with external causes. Substances that trigger allergic responses are antigens. These are often proteins that can be found in air, food and water. Airborne antigens such as plant pollens or house dust are well known. Other airborne antigens and food antigens are less obvious.
The first distinction that recurs in the allergy literature is between immediate and delayed patterns of allergic reactivity that loosely correspond to IgE-mediated allergy and non-IgE mediated responses. Many authors refer to the original four categories of immune-mediated injury defined by Gell and Coombs. The concept of four mechanisms is just a starting point for understanding immune-mediated disease. These very complicated defense-injury sequences cause a variety of disease states. The immediate or type 1 allergy pattern is easily recognized because it involves quick and dramatic symptoms. Hay fever is the most common type 1 allergy and can be diagnosed by allergy skin tests and by IgE antibody tests such as RAST or ELIZA. Delayed patterns of allergy are not so obvious and generally go unrecognized. Allergy skin tests do not show this problem. Symptom onset is delayed many hours after exposure to the trigger. Allergic reactions to drugs such as penicillin and to foods are delayed hypersensitivity.
Type 1 Hypersensitivity
Common allergy is the immediate or type 1 pattern that can largely be attributed to IgE and a sub-population of immune cells, the mast cells and basophils. These cells degranulate if sufficient antigen reacts with IgE antibodies which act as receptors on the cell's surface. Allergy skin tests detect mast cells armed with antigen-specific IgE. Patients who tend to have type 1 reactions are easily identified by their history; they tend to have hay fever, asthma, and eczema as do family members. This triad of allergic manifestations has been called "atopy". An inherited tendency to make excessive amounts of IgE antibody is one characteristic of some atopic individuals. Skin tests are useful in diagnosing inhalant allergies in atopic patients and will reveal some but not all food allergy. Type 1 food allergy produces immediate, dramatic symptoms, easily recognized by patients. Typical type 1 food reactions are anaphylaxis, hives, acute abdominal pain, vomiting and diarrhea
Allergic rhinitis is the most obvious environmental disease. Hay fever is the prototype of Type I allergy. The mechanism was thought to be a straight forward histamine-mediated response to inhaled antigens such as tree and grass pollens. Drugs that block histamine are effective in relieving hay fever symptoms. The early, immediate response is sneezing and anterior nasal discharge, often profuse. Hay fever is the most clear-cut case of allergy. Ads for antihistamines proclaim the simplest mechanism of allergy: an inhaled allergen (antigen), grass pollen, meets antibody-coated mast cells waiting in the mucosal surface of the nose.
A typical hay fever attack with sneezing, itching, and nose congestion results. A similar reaction in the throat produces soreness, mucus flow, swelling, and difficulty in swallowing and breathing (pharyngitis, laryngitis). A similar reaction in the lungs produces cough, mucus obstruction to airflow, and asthmatic wheezing (bronchitis, asthmatic bronchitis).
How to Use the Allergy Center
Begin with the Introduction to Allergy that provides essential knowledge.
There are at least two kinds of allergies the immediate and the delayed patterns. To understand the distinction better, click on the section that compares and contrasts Allergy Types.
If you are interested in Airborne Allergy,
go to that section to learn more about hay fever and asthma.
If you are interested in Food Allergy, then click on the section devoted to that complicated and fascinating subject.
Allergic reactions to drugs resemble food allergy more than inhalant allergy. Click on hay fever, asthma, rhinitis, otitis media, atopic dermatitis, urticaria, and anaphylaxis for more information.
Listen to Allergy as Hypersensitivity Diseases
The list of immune-mediated disorders is very long. To learn more about conditions disorders and diseases that have an immune basis go to all discussions of Allergic Disorders and Diseases
Immunology is a complicated subject that grows more dense and interesting every day. Most MDs will have a rudimentary knowledge of immunology and even the experts tend to specialize in one specific area because the field is so vast. It is possible for a smart reader to learn some basic concepts that make the subject somewhat comprehensible. Our emphasis is in providing information that's useful for self-management and for making decisions about your treatment options. Immunology Notes is an excellent introductory course..
The section on Diagnosis and Tests will steer the reader away from tests that look quick and easy but are invalid. The diagnosis of food allergy is the biggest, unsolved challenge. Physicians often default in the diagnosis and treatment of food-related illnesses and non-medical practitioners have launched careers in the food and chemical "sensitivity" business, using diverse and sometimes bizarre method of diagnosis and treatment.
Several Books in the Alpha Nutrition Health Education Series provide more detailed examination of specify problems such as skin and gastrointestinal disorders and celiac disease.
Hypoallergenic Nutrient Formulas
Alpha Nutrition Formulas are hypoallergenic; they are gluten free and do not contain cows milk, soya, or egg