Acute inflammation is the early response of the body to short-term adverse stimuli and is not specific, involving dendritic cells, Kupffer cells, histiocytes, resistant macrophages, and mast cells in response to physical or chemical damage or pathogen invasion. Chronic inflammation is the prolonged inflammatory response lasting months or years, is specific involving acquired immunity, and responds to prolonged irritation by microorganisms through fibrosis and angiogenesis involving macrophages, neutrophils and lymphocytes.