Section 4
Innate Defenders
By Boundless
![Thumbnail](../../../../../../figures.boundless-cdn.com/6682/square/complement-pathways.jpg)
The complement system helps or "complements" the ability of antibodies and phagocytic cells to clear pathogens from an organism.
![Thumbnail](../../../../../../figures.boundless-cdn.com/8767/square/man-interferon-alpha-2b-01.jpg)
Interferons (IFNs) are proteins made and released by host cells in response to the presence of pathogens.
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Natural killer cells (or NK cells) are a type of cytotoxic lymphocyte critical to the innate immune system.
![Thumbnail](../../../../../../figures.boundless-cdn.com/15971/square/-receptor-pathways-revised.jpeg)
Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system as well as the digestive system.
![Thumbnail](../../../../../../figures.boundless-cdn.com/15977/square/protein-tf-pdb-1a8e.jpg)
Iron binding proteins of the innate immune system include lactoferrin and transferrins.
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Antimicrobial peptides are an evolutionarily conserved component of the innate immune response and are found among all classes of life.
![Thumbnail](../../../../../../figures.boundless-cdn.com/1929/square/viral-myocarditis-281-29.jpeg)
In autoimmune heart diseases, the body's immune defense system mistakes its own cardiac antigens as foreign, and attacks them.