Inflammation is a complex host reaction to injury or to invasion by a wide variety of agents. The agents may be biological or chemical, living or non-living. Inflammation is sub-grouped into acute and chronic. Acute inflammation represents the immediate physiological tissue and host immune response to injury or infection and constitutes the initial step to limit tissue injury. Exaggerated reactions paradoxically result in more tissue damage and widespread effects associated with death and chronic illness. Chronic inflammation is either the consequence of repeated injury/exposure or of a non-productive immune response resulting from failure of the body's mechanisms to terminate inflammatory responses or prevent autoimmune reactions. This may lead to chronic organ injury and high morbidity.

Distinct inflammatory pathways exist in the human. The pathways and events depend on many factors, including the nature of the inciting stimulus and portal of entry, as well as the immune status and other biological characteristics of the host. Immune cells and inflammatory mediators control individual events of the process. A given immune cell or mediator may have direct effects and also give rise to other cells or mediators, resulting in an integrated, amplified response. The outcome may be beneficial, detrimental, or both. Detrimental consequences of autoimmune diseases occur because of immune cell mediated inflammation, directed towards the host's own tissues.

With rapid advances in molecular biology allowing increased understooding, it is clear that a wide range of disease states are based upon inflammatory and immune mediated factors. “Black-box” diseases such as multiple sclerosis, inflammatory bowel disease, and rheumatoid arthritis are now being described at a molecular level and understood to be the result of immune mediated, inflammatory processes. Diseases previously thought to be unrelated, such as coronary artery disease, are now understood to have powerful inflammatory or immune components. As this knowledge increases, the ability to provide drugs that truly modify and prevent disease processes will also increase. Such therapies will markedly improve or eradicate disease states. They will also ultimately lower the overall costs of disease care and return patients to levels of productivity that current therapies are unable to attain.