"Besides providing a broad range of protection against infection, components of innate immunity respond to tissue injury; they promote repair, contribute to the genesis of autoimmunity, respond to vaccines, and watch for cancer. Beyond these clearly immunological conditions, innate immunity is implicated in allergy, atherosclerosis, malignancy, obesity, and osteoporosis-conditions that plague many patients including transplant recipients.

The innate immune system is first in the line of host defense. As molecular research developed, the evolutionary origin of the molecules involved in innate immune mechanisms was revealed to be ancient. According to the neo-Darwinian theory of evolution, spontaneous mutagenesis is the driving force of biological evolution, while the direction of evolution depends on natural selection together with the available genetic variants.

The evolution genes provide evolutionary fitness to the organisms. Innate immunity seems to have evolutionarily developed into ´today´s fitness´. This defense system , although composed of many heterogenous systems whose evolutionary origins are poorly defined, originated early in phylogeny, before the separation of plants and animals ..."

Innate Alloimmunity. Part 1: Innate Immunity and Host Defense
Land, Walter G.
Pabst, 654 pages