Sep 24, 2008

The types of allergic reactions

Type I allergic reaction (immediate-type reaction, reagin, anaphylactic, atopic type).
It develops with the formation of AT-reagin belonging to the class of IgE and lgG4. They are fixed on the mast cells and basophilic LEUKOCYTES. In connection with reagin allergen of these cells are mediators: histamine, heparin, serotonin, thrombocyte-activate factor, prostaglandin, leukotriene and others, defining the clinic immediate allergic reaction type. After contact with specific clinical manifestations reactions occur after 15-20 minutes.
Allergic reaction type II (cytotoxic type). The type is characterized by the fact that AT formed to cells and tissues before IgG and IgM. This type of reaction called only AT, the ability to enhance complement. AT connected with the modified cells of the body, leading to activation of complement reaction, which also causes damage to and destruction of cells with the subsequent phagocytosis and their Disposal. It is for cytotoxic type of allergy drug development takes place.
Allergy type III (tissue damage immune systems - the immune complex type). There is as a result of circulating immune complexes, which were composed of IgG and IgM. AT precipitating called this class as they form precipitate when connecting to the AG. This type of reaction is the lead in the development of serum sickness, allergic allergic [hypersensitivity] pneumonia, drug and food allergies, with auto-allergic diseases ( Rheumatoid arthritis and others).
Allergic reaction type IV or delayed-type allergic reaction (hypersensitivity delayed-type hypersensitivity cell).

With this type of reaction the role of AT perform sensitized T-lymphocytes that have receptors on their membranes that can specifically interact with the sensitizing AG. In connection with lymphocyte allergen are mediators cellular immunity - LYMPHOKINE. They cause congestion of macrophages and other lymphocytes, which is causing inflammation. One of the roles of mediators was to involve them in the process of destruction AG (alien microbes or cells) that sensibility lymphocytes. Reactions slow-growing type in the body sensitized through 24-48 hours after contact with allergen. Cell type of reaction is at the heart of the development of viral and bacterial infections (tuberculosis, syphilis, leprosy, brucellosis, tularaemia), some forms of infectious-allergic bronchial asthma, rhinitis, transplant and antitumor immunity. Pathogenesis of allergic-type reactions slow due to the interaction SENSITIZED lymphocytes with specific allergen. The mediators formed cellular immunity impact on macrophages, to involve them in the process of destruction AG, against whom sensitize lymphocytes. Clinically it is manifested development hyperergic inflammation: there is a cell infiltration, cell constitute the basis mononuclear which - lymphocytes and monocytes. Uninucleate infiltration expressed around the small blood vessels. It should be noted that for the allergic inflammation of the most characteristic fibrinoid degeneration. Allergic inflammation is regulated by the nervous system, and its intensity depends on the reactivity of the body.

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