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Trying to provide all necessary information about IMMUNITY and IMMUNE SYSTEM

Immune Dysfunction and Its Consequences|Immunology| Immune system

Posted by Mumtaz khan Thursday, 15 March 2012

The above overview of innate and adptive immunity depicts a miuticomponent interactive system that protects the host from infectious diseases and from cancer.This overview would not be complete without mentioning that the immune system can function improperly.Sometimes the immune system fails to protect the host adequately or misdirect its activities to cause discomfort common manifestations of immune dysfunction:

* Allergy and asthma
* Graft rejection and graft-versus-host disease
* Autoimmune disease
* Immunodeficiency

Allergy and asthma are results of inappropriate immune responses,often to common antigens such as plant pollen,food,or animal dander.The possibility that certain substances increased sensitivity rather than protection was recognized in about 1902 by Charles Richet,who attempted to immunize dogs against the toxins of a type of jellyfish,physalia.He and his colleague Paul Portier observed that instantly,and fatally,to subsequent challenge with minute amounts of the toxin.Richet concluded that a succesful immunization or vaccination results in phylaxis,or protection,and that an opposite result may occur- anaphylaxis-in which exposure to antigen can result in a potentially  lethal sensitivity to the antigen if the exposure is repeated.Richet recieved the Nobel Prize in 1913 for his discovery of the anaphylactic response.
Fortunately,most allergic reactions in humans are not rapidly fatal.A specific allergic or anaphylactic response usually involves one antibody type,called IgE.Binding of IgE to its specific antigen (allergen) releases substances that cause irritation and inflamation.When an allergic individual is exposed to an allergen,symptoms may include sneezing,wheezing,and difficulty in breathing(asthma);dermatitis or skin eruptions(hives);and,in more extreme cases,strangulation due to blockage of airways by inflammation.A significant fraction of our health resources is expended to care for those suffering from allergy and asthma.The frequency of allergy and asthma in the United States place these complaints among the most common reason for a visit to doctor's office or to the hospital emergency room.
When the immune system encounters foreign cells or tissue,it responds strongly to rid the host of the invaders.However,in some cases,the transplantation of cells or an organ from another individual,although viewed by the immune system as a foreign invasion,may be the only possible treatment for disease.For example,it is estimated that more than 60,000 persons in the United States alone could benefit from a kidney transplant.Because the immune ayatem will attack and reject any transplanted organ that it does not recognize as self,it is a serious barrier to this potentially life-saving treatment.An additional danger in transplantation is that any transplanted cells with immune function may view the new host as nonself and react against it.This reaction,which is termed graft-versus-host-disease, can be fatal.The rejection reaction and graft -versus-host disease can be suppressed by drugs,but this type of treatment suppresses all immune functions,so that the host is no longer protected by its immune system and becomes susceptible to infectiuuos diseases.Transplantation studies have played a major role in the develpoment of immunology..
In certain individuals,the immune system malfunctions by losing its sense of self and nonself,which permits an immune attack upon the host .This condition, autoimmunity, can cause a number of chronic debilitating diseases.The symptoms of autoimmunity differ depending on which tissues and organs are under attack.


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