The innate immune response is nonspecific and provides an initial and rapid (hrs) response to infections by other organisms, but does not provide long-lasting immunity. Its 5 key functions include:

1. Recruiting immune cells to sites of infection, through the production of factors, including cytokines

2. Activating the complement cascade

3. Removing foreign substances present in organs, tissues, blood and lymph, by WBCs

4. Activating the adaptive immune system through antigen presentation

5. Providing a physical and chemical barrier to infectious agents