Although it is unknown what causes most types of vasculitis, immune system abnormality, inflammation of blood vessels, and genetic factors appear to be somewhat important in the cause of the disease. Vasculitis can also be caused by an immune or allergic reaction in the vessel walls.
Allergic reaction: The hypersensitive response of the immune system of an allergic individual to a substance. When an allergen enters the body, it causes the body's immune system to develop an allergic reaction in a person with an allergy to it. This reaction can occur when the immune system attacks a normally harmless substance (the allergen). The immune system calls upon a protective antibody called immunoglobulin E or IgE to fight these invading substances.
An allergy is a response by the body's immune system to something (called an allergen) that is not necessarily harmful in itself. Certain people are sensitive to this allergen and have a reaction when exposed to it. During an allergic reaction, a complex series of events occurs within the body.ome people who have had a severe allergic reaction or anaphylactic reaction in the past carry an adrenaline (epinephrine) pen. This can be self-injected or injected by a bystander, in the event of anaphylaxis. Anaphylaxis is the name given to an extreme form of allergic reaction.