Allergy

The allergy is an exaggerated immune response to a foreign substance to the body, ie an immunologic hypersensitivity to a specific external stimulus. Individuals with allergies are called "atopic" or more popularly "allergic".
The body tissue or cell capable of presenting a hypersensitivity reaction is said to be sensitized. Allergic reactions, and immune reactions, are highly specific, reacting only to the body sensitized antigenic determinant used as immunogen or similar structure. Hypersensitivity reactions were early separated into two different types, according to the time elapsed between the body contact with the antigen sensitized and macroscopic visualization of allergic phenomenon. Thus, while calls immediate hypersensitivity reactions require only minutes or a few hours for his appearance, delayed hypersensitivity reactions develop only after many hours. Today, although the time of onset criterion remains valid for the classification of hypersensitivity reactions, it is known that the most important differences separate the two types. Thus, while the reactions of immediate type reactions include all playable by one or another of the various types of antibodies present in the serum and thus can be transferred from one individual to another by antiserum, the reactions depend on delayed-type lymphocytes and therefore are not transmitted by antiserum, but only by cells. The transfer of cells by means of a state of immunity is called immunization adoptive recipient organism because adopts the donor cells, which confer immunity acquired in another organism. In case of transfer of cells from a state of hypersensitivity, is said to be adoptive sensitivity. Both awareness adoptive immunity is only possible among inbred individuals. (It is possible to transfer of allogeneic cells which, however, survived for a short period.) Note that while the delayed hypersensitivity is transferable by antibodies or cells.