Immunoglobulins, also known as antibodies, belong to a class of serum protein called gamma globulins.  Immunoglobulins are secreted by plasma cells derived from B lymphocytes in response to antigenic stimulation, and play an essential role in neutralising and mediating the removal of foreign substances and pathogens in humoral immunity.

There are 5 main classes of immunoglobulin, IgM, IgG, IgA, IgD and IgE, which have different structures, properties and functions.  IgG is the most abundant immunoglobulin, and constitutes the major mature humoral antibody response.

Immunoglobulins (IgG) fractionated from human plasma are important biological medicines.  Therapeutic immunoglobulins include ‘normal’ immunoglobulins produced from unselected donors, and ‘specific’ immunoglobulins produced from selected hyperimmune individuals with high levels of antibodies with particular antigen specificities. Immunoglobulins may be administered intramuscularly (IMIG) or, for infusion of large volumes, by the intravenous route (IVIG).

Used initially as replacement therapy for primary and secondary immunodeficiencies, normal intravenous immunoglobulin is also widely used for treating a range of autoimmune and inflammatory disorders, such as Idiopathic thrombocytopenic purpura (ITP), Kawasaki disease (children), Chronic Lymphocytic Leukaemia (CLL) and many other diseases which continue to put pressure on supply which is already limited.

Specific immunoglobulins include anti-D immunoglobulin, for the prevention of haemolytic disease of the newborn; Hepatitis A and B for prophylaxis of hepatitis; Rabies, Tetanus and Varicella zoster immunoglobulins are also used for prophylaxis for the diseases they protect against.  Monoclonal antibodies produced in vitro also have clinical applications and considerable potential for increased therapeutic use.