Skip to main content

Immune Dysfunction


Anaphylaxis is a severe, life-threatening, generalised or systemic hypersensitivity reaction, with significant disturbance of one or more of airway, breathing or circulation. It is not clear why one person with specific immunoglobulin E (IgE) to an allergen will have an anaphylactic reaction on exposure, another only a local reaction, and in a third individual no reaction at all.


Allergy is a harmful, misguided and over-zealous immune response to antigens that causes tissue damage and disease. It is a form of hypersensitivity, which can be classified into four types, based on the immune reactant, the antigen type and the effector mechanism (Table 1): it can be considered as a type of autoimmunity. An extreme example of allergy is anaphylaxis. Antigens that can induce an allergic response are called allergens, and they are often derived from non-infectious or non-microbial sources.