Innate immune responses are not specific to a particular pathogen or non-self-ingredient in the way that the adaptive immune responses are. They depend on a group of proteins and phagocytic cells that recognize conserved features of pathogens and become quickly activated to help destroy invaders. The innate immune system is essentially made up of barriers that aim to keep viruses, bacteria, parasites, and other foreign particles out of your body or limit their ability to spread and move throughout the body.
General Immune Responses
Phagocytes & Macrophages
The Complement System
Pathogen sensing and restriction
Pathological inflammation in response to microbes