The innate or natural immune system is that part of the immune system that we are born with. The innate immune system keeps out invading organisms (pathogens) such as viruses, bacteria and fungii via a number of mechanisms. These include
Innate immunity is always present in the body and can react very quickly to an infection. The fact that it is non-specific allows it to target most invaders without previously having come across them.
The division between the innate and acquired immune systems is far from complete and there are several interactions and feedback mechanisms in operation between the two. These include cytokine secretion, antigen presentation and cell-to-cell communication.
Innate Immunity Links:
Non Specific "Innate" Immunity
Innate Human Immunity
Interrelationship between innate & acquired immunity
Innate versus adaptive immunity