Allergies And The Immune Response

Allergies and the Immune Response

The immune system, made up of the thymus, lymph nodes, spleen, tonsils, and white blood cells works as a network of chemical signals day in and day out as the body's own natural defense system against a number of pathogenic substances. Ranging from a variety of bacteria, parasites, and viruses, the body's immune system kills and destroys the majority of these potentially harmful pathogens. However, as efficient and effective as the immune system is, in some instances it doesn't always work properly resulting in flaws that can become quite troublesome for many around the world. One of these problems may not come from the threat of harmful bacteria or viruses, but rather from things that many people overlook and dismiss as a part of everyday life. The problems are allergies and allergic reactions; These range from seasonal allergies, caused by pollens, dust, rag weeds and animal hairs, to some of the more severe types caused by a variety of foods and insect bites, which have the potential of being deadly if untreated. Whether it is an annoying runny nose or a risk of one's own life, these allergies and reactions are dealt with and suffered by millions of people around the world.

The immune system usually does a good job recognizing and destroying germs, viruses and other foreign agents that can attack the body. But to those that have allergies, their immune system occasionally misreads the signals and responds to harmless substances such as pollens, molds or foods as if they were harmful. Why people become sensitive to these substances isn't known, but studies have shown that the tendency to develop allergies is inherited. Also repeated or prolonged exposure to a specific substance may be responsible to trigger a reaction. The most common type of allergies are the seasonal allergies and hay fever allergic reactions that are associated with the pollens, dust, weeds, animal furs, molds, mites, etc. These allergens are usually responsible for a very common symptom called allergic rhinitis, which is a condition that causes signs and symptoms such as sneezing and runny nose. It occurs after exposure to one or more specific airborne allergy causing substances. When one of these allergens enter the body for the first time they activate TH2 cells and also stimulate IgE class switching in B cells. IgE is then produced in B cells which then bind to mast cells. As repeat exposure to the allergen occurs they bind to the IgE antibodies that are located on the mast cells which in turn stimulates the release of chemical mediators such as vasoactive amines, lipid mediators, and cytokines. These chemicals are responsible for the sneezing, runny nose, itchy eyes, hives, swelling, shortness of breath, wheezing, and other signs and symptoms of allergies. The B cell lymphocytes that respond to these types of allergies serve a very important role in the effectiveness of the immune system. They circulate throughout the body looking for foreign invaders to initiate an immune response to kill the unwanted pathogen. The B cells are stimulated to produce antibodies accordingly which then themselves can identify the allergen. An antibody is composed of a protein called an immunoglobulin. There are five different types of immunoglobulins: IgA, IgE, IgM, IgG, and IgD, each specific for recognizing certain pathogenic invaders. However, igE is the one most often involved in allergic responses. The antibodies that are produced by the B cells then attach themselves to other types of white blood cells that are called mast cells and basophils, which are found in the respiratory, gastrointestinal tracts, and in the skin. It is the effect of these certain antibodies combined with mast cells that induce a chemical response which triggers the release of a number of chemicals, one of which is generally most common is histamine. It is the release of this chemical, along with others which then is turn produces the allergic reaction response. For instance, when these chemicals are excessively released in the lungs it causes muscle spasms of the muscle lining of the mucosal wall which then leads to the production of mucus and the narrowing and swelling of the lining of air passageways. This may then result in coughing, sneezing, wheezing, and occasionally shortness of breath. In the nose or sinuses chemicals called leukotrienes along with histamine are released and react with tissue cells of the epithelium that cause symptoms of runny nose, teary eyes, or itchy nose, eyes or throat. In the skin of those who are allergic, allergens weaken the skins natural barrier function. Allergic skin looses the ability to be a protective barrier because of inflammatory white blood cells that take up residence in the skin releasing inflammatory mediators that weakens the skin and causes hives and other rashes. In the stomach a number of mediators are released in response to food sensitivity. Mediators such and ovoalbumin and lactoglobulin can act in the same fashion as such antigens released from parasites that cause a similar allergic response. These chemicals along with other will in most instances produce fever; sweets, fatigue, and cognitive dysfunction in those witch food allergies because the gastrointestinal tract has now become permeable leaking some antigens into then bloodstream. In some serious instances, the allergic reaction may result in anaphylaxis and anaphylactic shock, which is a life threatening condition in which blood pressure substantially drops and breathing becomes very difficult.

Affecting two out of every ten people, seasonal allergies are responsible for the many symptoms that arise from the naturally abundant allergens that can be quite uncomfortable and irritating to many individuals. Hay fever refers to the symptoms that accompany these types of allergic reactions. Hay fever encompasses the itchy red eyes, runny nose, coughing, and sneezing. Hay fever is an allergic reaction that is the immune system's response to foreign material in the air that people breathe. This reaction is triggered once an allergen enters the body by means of inhalation or direct contact with the lining of the eyes and ears. The white blood cells of the immune system produce antibodies to the offending substance. The antibodies then attach themselves to mast cells throughout the parts of sinus cavity and surrounding areas that are being affected by the invading antigen. Constant exposure releases chemical mediators that induce the allergic response associated with hay fever. These include watery eyes, runny nose, sneezing, itching of the eyes and throat, and coughing. This overreaction to a harmless substance is often called a hypersensitivity reaction. The most common allergens to cause this type of allergic reaction are pollens. Pollens