Introduction
Whereas acute inflammation is neatly defined by its four cardinal features and the presence of neutrophils, chronic inflammation resists such a succinct summary.
Chronic inflammation is a form of response to infection and injury that differs from acute inflammation by the timeframe over which it operates and by its main cellular constituents.
Acute inflammation develops quickly once it has been triggered. If the injury or infection can be resolved by the process of acute inflammation, this successful outcome occurs soon after the inflammation has begun, typically within hours to days. By contrast, chronic inflammation is a longer lasting process that implies some form of infection or injury that cannot be neutralised quickly by acute inflammation.
Whereas neutrophils are intimately associated with acute inflammation, the characteristic cells of chronic inflammation are lymphocytes.
Chronic inflammation tends to involve elements of the acquired immune system while acute inflammation is dominated by the innate immune system.
The chronic inflammatory system has several components that interact with each other.
Aberrant activity of the chronic inflammatory system produces two main patterns of disease hypersensitivity and autoimmune disease.