Immune Dysfunction

B cells play an important role in regulating  the immune response in both physiological and pathological conditions. Dysregulation of B-cell function can lead to severe consequences for the host, which are discussed below.

The immune response in autoimmune disease recapitulates that of responses directed against infection, except that self antigens are, or become, the target of the adaptive immune system. 

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.