| Allergy can be defined as an inappropriate reaction of the immune system. The allergen is either inhaled, ingested or comes in contact with the skin and is almost invariably a protein or a molecule linked to a protein (hapten), that the immune system recognises as foreign to the body (1). The science of immunology probably started with Jenner's classical study of the role of vaccination in protection against smallpox virus in 1798. Clinical immunology emerged from the 1950's onwards and addressed the nature of the immune response in infective diseases, autoimmunity, organ transplantation, different organs and tissues (2).
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