Epidemiological surveys have indicated an increase in allergic diseases. The increase in these allergic diseases has become a big social and economical problem and people and governments are losing time and money, besides having psychological affects.
It is believed that changes of environmental surroundings are the main cause for these diseases. Environmental changes such as migration to new places and climates, westernization of food, pollution, food additives, excessive use of cosmetics and medicines, excessive stress are the causes of an increase in such allergic symptoms.
Allergens are substances from foods, plants, environment or animals that inflame the skin because the immune system over-reacts to these substance. Inflammation occurs even when the person is exposed to very small amounts of the substance for a limited period of time. Some examples of allergens are pollen and pet's dander (tiny particles from the animal's skin or hair).
Allergic reactions are classified into from type I to type IV depending on the causative immunoglobulins and cells participating therein. The types I to III allergies are immunological reactions in which human antibodies participate. They are called immediate-type allergies, since allergic reactions appear immediately upon contact.
The type IV allergy is a cell-mediated immunological reaction in which instead of an antibody, sensitized lymphocytes participate. It is also called delayed-type allergy. Allergic reaction of type IV is a reaction of a delayed type in which T cells (small white blood cells that orchestrate and/or directly participate in the immune defenses, also known as T lymphocytes) receiving an antigen information via antigen-presenting cells and release various cytokines whereby an inflammation reaction of a delayed type takes place.
Allergic contact dermatitis is a typical disease, which occurs due to an allergic reaction of type IV. Steroid compositions are used for the therapy of allergic diseases of type IV and such steroid compositions suppress the production of cytokine in T cells and show a dramatic effect for the therapy of eczema. On the other hand however, there is a possibility that they cause severe adverse actions such as thinning/sensitizing of skin, sleeplessness, photosensitivity, decrease in adrenocortical function etc by long period administration.
An example of an allergic and immunology mediated skin disease is psoriasis. Recent researches indicate that psoriasis is likely a disorder of the immune system. This system includes a type of white blood cell, called a T cell, that normally helps protect the body against infection and disease. Scientists now believe that, in psoriasis, an abnormal immune system causes activity by T cells in the skin. These T cells trigger the inflammation and excessive skin cell reproduction seen in people with psoriasis. Many of the pathological and histological findings of this disease are equivalent to those of dermatitis (eczema). Psoriasis is frequently worsened and becomes chronic by external stimulus. In each case, it is the fundamental therapy to control the skin symptoms to thereby prevent worsening.
Common treatments for Psoriasis are corticosteroids, calcipotriene, anthralin, topical retinoid, coal tar, salicylic acid etc. All of these treatments have side effects and become ineffective when used in for long period of time.
Pharmaceutidal compositions for allergic and immunology skin diseases have already been developed and being used for the therapy but, they have adverse reactions hence, there has been a strong demand for compositions derived from natural products where a long-term administration is possible, safety is high and no adverse reaction takes place.
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