
The Ancient Immune System from a Starfish Point of View
There are two primary and vital aspects of our immune system – adaptive immunity and innate immunity. The innate immune system includes proteins and cells that are always active to combat microorganisms as soon as they detect an infection. The adaptive immune system, on the other hand, gets called to act when the pathogens circumvent the innate defenders.
Invertebrates typically lack the adaptive immunity that is possessed by vertebrates. However, in the 19th century Elie Metchnikoff, a Russian biologist, discovered the presence of the innate immune system in invertebrates. He pierced a starfish larva using a rose thorn. The very next day, he found tons of tiny cells try to cover the thorn. Since its evolution somewhat 5000 years ago, starfish have remained virtually unchanged. This was long before vertebrates where discover, meaning the innate immune system has strong ancient roots.