From Computer Tyme Support Wiki

Introduction

We all know what the function of the immune system is. The immune system is there to protect the stuff that we are made out of and to get rid of the stuff that will cause us harm. But how does it work? How does it know who is the good guys and who is the bad guys? How does it tell friend from foe?

There are thousands of papers written about the immune system. They talk about the different cells involved. They talk about proteins, peptides, antigens, antibodies, vaccines, bone marrow, self vs. non self, signaling pathways, apoptosis, and hundreds of other concepts that will make your head spin. This paper is different. This paper talks about the immune system in the context of function and process rather than focusing on the mechanisms of how it works. In this article I compare the immune system to an email spam filtering system which functions as an engineered immune system for email.

The goal here is to look at the big picture and work back to the details. An email spam filtering system and the human immune system ultimately have to accomplish the same things, to identify the good and the bad and to protect the good and eliminate the bad. Although one is a biological mechanism created by evolution and the other is entirely software, on a functional basis they are extremely similar, even though the mechanisms are totally different. Both systems have innate and adaptive mechanisms where the innate system is fast and rule based and the adaptive system is programmable and can learn friend and foe dynamically.

The Immune System is an Information Processing System

The main point I hope to get across here is that the immune system is an information processing system. We think of the brain and nervous system as being the center of learning and decision making. But as it turns out it isn't the only intelligent system in the body capable of learning. Although the immune system isn't the center of conscientiousness or self awareness or thinking, it is a programmable computing device that is capable of learning and making sophisticated decisions.

In fact, one could argue that the brain is an integral part of the immune system. When one someone becomes sick enough our brain decides that we should call the doctor who prescribes and antibiotic that kill the infection that is attacking us. And it's not just limited to our own brain. The antibiotic exists because of the work of many minds working as a team within a global society to invent, manufacture, and distribute this medicine to those who need it. Between antibiotics and the invention of the flush toilet our extended immune system has doubled our human lifespan. Our excretory system used to end at the anus, but today that is extended to the toilet, the sewage system, and the sewage treatment plant. And although these systems aren't physically or biologically connected to us, it would be a mistake to treat these systems and separate from us just because they don't contain human DNA. My body is a colony of organisms and 90% of those critters and non-human, yet I could not live without them. So are they "self" or foreign? Or does self and foreign really have any meaning? Is a bee a single organism or is the organism the hive which is made up of bees?