People in underdeveloped countries are very susceptible and face exposure to a wide array of pathogens that is why the production of IgE has a protective value. The production of IgE is the issue for the young person we have talked about, in her allergy to cats. The first signs of an allergy are usually not evident and there are no visible symptoms, and this stage of allergy development is called sensitization as the body is undergoing the first immunological reactions. Unfortunately, her immune system is developing the first signs of an immunological reaction and a lot of IgE antibody molecules are being actively produced inside her. The mast cells in the bone marrow are the places these antibodies attach themselves to, these mast cells are part of the connective tissue in the body, and they are heavily distributed especially near the small blood vessels in the tissue that lines such organs like the skin and the intestines, this tissue is known physiologically as the epithelial tissue. A type of white blood cell or WCB also known as a basophils, is the vehicle that the antibody uses for transport as they can penetrate the small blood vessels, these then form around the foreign particles to destroy it. The mast cells and basophils are where the antibodies are now attached and these in turn resemble more and more, mobile grenades fully provided with ammunition, which includes such biological additives such as the anti-allergic substance histamine and a variety of allergy alleviators. For this allergy to begin, it needs a trigger of a new invasion from the allergen, the activators of this allergic reactions from the cat dander, which will eventually set off and activate those grenades which would in the course of time set off the dangerous symptoms and evidences for cat allergy and the reactions produced the following symptoms are the typical results which include a burning the eyes, symptoms of sneezing and other attendant cold type of symptoms. This stage is characterized by the appearance of serious and acute symptoms and is considered the second stage of the allergic process, within the human body. The design of the IgE antibodies is tuned to recognize and attach to the specific allergen that is the cause of their beginning. The Y-shaped IgE molecules resemble all other antibodies in being typically a known shape; that is that their bases are attached to the basophil cells or as they are known; the mast cells, and they have the arms extending outward as is typical. A cascade of substances is released when the incoming foreign bodies trigger and attach themselves to at least two IgE bodies, thus beginning the allergic reaction and resultant symptoms. Histamine is the most important of these substances; it is active in the dilation of blood vessels and brings about shock in very extreme cases. Shock, besides brining about a redness in the affected part, it's release can also severely impair normal breathing because of it's constriction of the bronchial tubes and at the same time it can unduly irritates nerve endings, causing much pain and itching sensations. All these reactions can bring about the increase in the production of mucus in the respiratory system, thus these symptoms are very informative while at the same time causing itching and pain; and stimulating the production of mucus in the respiratory system. It is therefore important to remember why histamine is so well studied in the development of an anti allergic drug. The study of histamine is very important considering it's harmful effect on most parasites and has been considered indispensable ever since the plague of worms and their regular identification inside the human body. The effectiveness of histamine within the human body is extremely well researched and since histamine is also known to be toxic to most human internal parasites, those who are active in the field of parasitic worms consider its study very expedient. There is late-phase reaction in the history of allergy development, a delayed, sometimes prolonged period of immune activity also considered to be the third stage in the process of the allergen's reaction to the human body. Other types of WBC's or the so called eosinophils play a major role in this stage, these eosinophils play a role by way of an elevated eosinophil count which can help to diagnose the presence of an allergic reaction in the human body. Damaged tissue and inflammation are caused by the two kinds of basophils and eosinophils, along with other types of white blood cells in the region of the allergic reaction. As an allergen, this may thus cause an acute asthma attack once it reaches the vicinity of the lungs. Any foreign substance capable of causing an immune system reaction is called an antigen, the reaction of the immune system to this particle or organism is what produces antibodies within the human body. Therefore special types of allergens are known antigens and they almost always cause an allergic reaction within the human body. As such very common allergens may be things that are quite abundant in the living space, things that include animal dander, pollen from flowers, bee venom if stung, from humid areas; mold spores, and different foods-stuffs and medications, including common items such as penicillin and peanuts. Most antigens and thus the allergens have to find their way into the human body as invaders, in order to affect their human host's. The conjunctiva - the tissue that lines the eye's and the skin are very hard to penetrate, and they offer very solid protection against the antigen. Any reactions that the molecules of the allergen may have, for example cat dander with the skin are very limited and localized reactions, that is if there is any effect in the first place, the only symptoms the first time might be a slight rash and feelings of itchiness. Antibody formation can however be easily engendered by the use of different types of chemical compounds, which seem to penetrate the skin and travel through the body sensitizing it for antibody production, substances such as antibiotic creams often used topically may easily sensitize and cause antibody formation and consequent allergic reactions. Therefore an allergic reaction may later be experienced due to this usually in the form of a rash or fever or types of allergic manifestations. Access into the human body is very easily made through the respiratory and alimentary tracts by potential allergens and antigenic particles. Therefore the antigens or particulate matter breathed in or swallowed can very easily affect whole of the respiratory tract starting from the nose to the pulmonary system and even the alimentary canal up to the intestines starting from the lips. The causes of hay fever for example, is simple ragweed pollen which can be breathed in through the nose accidentally by a person very sensitive to the matter besides the incident hay fever. Asthma can also be provoked and started through the presence of animal dander just as hay fever can when an allergic reaction has set in. The bloodstream is the main transport system used by the allergen molecules in their escape from the confines of other systems by which they may have gained entry. Therefore hives and rashes may be activated by allergens present in food when they stimulate mast cells in the skin. A widespread reaction in the body may moreover, brought about by the histamine and other chemicals produced during an allergy. One case study has shown that in some rare cases, an allergen reach and cause difficulties even in the liver and kidneys and other remote organs from the site of reaction. Penicillin the common antibiotic was being administered to a patient in a large metropolitan hospital, for streptococcus infection, the patient consequently developed a fever, a rash came on, and there was blood in the urine. Which simply meant that the patient had developed an allergic sensivity to penicillin and hence kidney failure resulted. When prednisone, which is a steroid medication, used in the reduction of swellings and suppressing the immune system during allergy reaction was substituted instead of penicillin, renal function was restored.