Natural immunity is a type of innate immune response that is present from birth and does not require prior exposure to a pathogen.

Skin, mucous membranes, and stomach acid are all physical barriers of innate immunity that help to prevent pathogens from entering the body.

Lysozyme, interferon, and the complement system are all chemical barriers of innate immunity that help to kill or inactivate pathogens.

Neutrophils, macrophages, and natural killer cells are all cellular components of innate immunity that help to kill or phagocytize pathogens.

The complement system is a complex network of proteins that helps to opsonize pathogens, lyse pathogens, and activate inflammation.

Toll-like receptors (TLRs), C-type lectin receptors (CLRs), and NOD-like receptors (NLRs) are all types of pattern recognition receptors (PRRs) that help to recognize pathogens and trigger innate immune responses.

Interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) are all types of cytokines that are produced by innate immune cells and help to regulate the immune response.

Defensins, cathelicidins, and siderophores are all types of antimicrobial peptides that are produced by innate immune cells and help to kill or inactivate pathogens.

CD56bright NK cells, CD56dim NK cells, and NKT cells are all types of natural killer (NK) cells that help to kill or inactivate pathogens.

Conventional dendritic cells (cDCs), plasmacytoid dendritic cells (pDCs), and myeloid dendritic cells (mDCs) are all types of dendritic cells that help to activate adaptive immune responses.

Natural killer (NK) cells, group 1 ILCs, and group 2 ILCs are all types of innate lymphoid cells (ILCs) that help to regulate the immune response.

Toll-like receptors (TLRs), C-type lectin receptors (CLRs), and NOD-like receptors (NLRs) are all types of pattern recognition receptors (PRRs) that are expressed on the surface of phagocytes and help to recognize pathogens.

Neutrophils, macrophages, and dendritic cells are all types of phagocytes that help to engulf and destroy pathogens.

Interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) are all types of cytokines that are produced by macrophages and help to regulate the immune response.

Defensins are a type of antimicrobial peptide that is produced by epithelial cells and helps to kill or inactivate pathogens.