Simply put, your immune system can be thought of as having two branches:
- The innate (naturally occurring) immune system
- The adaptive (acquired) immune system
Although defined as separate branches they do work together and signals and cues provided by the innate immune response have a significant effect on the efficiency and strength of the response of the adaptive branch. In fact, there are certain types of cells (know as macrophages and dendritic cells) that perform an important bridging function between these 2 branches and adaptive responses would not be possible without these cell types.
While the innate immune system provides immediate, and in some ways a generalized defense against infectious agents, the adaptive immune response takes a bit longer to initiate, but once it is activated it provides very specific and long-lasting protection. Combined, the power of the two branches of the immune system offers large-scale protection from the world of foreign pathogens, as well as internal dangers such as cancer.
Reference: 1. Prendergast, GC et al. Cancer Immunotherapy: Immune Suppression and Tumor Growth. 2013. (Elsevier Science).
