page_title: Nonspecific immune cell
section_title: The Innate Immune System
hierarchical_section_title: Nonspecific immune cell / The Innate Immune System
caption_attribution_description: English: Simplified schematic diagram of Phagocytosis in three stages
context_page_description: A non-specific immune cell is an immune cell that responds to many antigens, not just one antigen. Non-specific immune cells function in the first line of defense against infection or injury. The innate immune system is always present at the site of infection and ready to fight the bacteria; it can also be referred to as the "natural" immune system. The cells of the innate immune system do not have specific responses and respond to each foreign invader using the same mechanism.
context_section_description: There are two categories to which parts of the immune system are assigned: the non-specific, or innate immune system and the adaptive immune system. The non-specific response is a generalized response to pathogen infections involving the use of several white blood cells and plasma proteins.  Non-specific immunity, or innate immunity, is the immune system with which you were born, made up of phagocytes and barriers. Phagocytosis, derived from the Greek words phagein, meaning to eat, kytos or cell, and “osis” meaning process, was first described by Élie Metchnikoff, who won the Nobel Prize 100 years ago.  Phagocytosis involves the internalization of solids, such as bacteria, by an organism.
  ]Macrophages, neutrophils, and dendritic cells are all cells of the innate immune system that utilize phagocytosis and are equipped with Toll-like receptors (TLR). Toll-like receptors are present on each of these cells and recognize a variety of microbial products resulting in the induction of more specific immune responses. When a phagocytic cell engulfs bacteria, a phagosome is formed around it and the entire complex is ultimately trafficked to the lysosome for degradation.  These cells that participate in the non-specific immune system response do not differentiate between types of microorganisms but do have the ability to discern between what is self and what is non-self.  The cells of this system are known as non-specific immune cells.
caption: Phagocytosis in Three Steps
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