A<unk>  is an<unk>  cell (such as a macrophage, neutrophil, or dendritic cell) that responds to many antigens, not just one antigen.<unk> s function in the first line of defense against infection or injury. The innate<unk>  system is always present at the site of infection and ready to fight the bacteria; it can also be referred to as the "natural"<unk>  system. The cells of the innate<unk>  system do not have specific responses and respond to each foreign invader using the same mechanism.
Nonspecific immune cell
Reactive lymphocyte
Naive T cell
Passenger leukocyte
Cancer-associated fibroblast
Dendritic cell
Mast cell
Cancer stem cell