Human Errors #6: Immune System

The immune system is something to marvel at. It is in a state of continuous alert and is fighting (minor) wars all the time, and wins most of its battles (which is why we are healthy most of the time). But it has its flaws, writes Nathan Lent in Human Errors.

 

The most well-known flaws are the diseases where the body attacks itself. No bacteria, virus, or tumours are the culprits. They are called autoimmune diseases.

“Autoimmune diseases are the result of mistaken identity… It’s a tragic case of friendly fire.”

 

Surprisingly, allergies too are an immune system “error”:

“An allergy is the result of the immune system overreacting to a foreign substance – one that is totally harmless.”

Redness, swelling, fever, pain – all signs of an allergic reaction – these are also signs of the immune system on overdrive. As Lent wryly remarks about those allergic to bee stings:

“Even if bee stings were truly dangerous (which they’re not), suicide seems like an overreaction.”

In extreme cases then, “immune systems are like ticking time bombs”.

 

But why do some develop such allergies whereas most don’t? For that, we need to understand how the immune system is “trained”. Step 1 happens when it’s still an embryo, a process called “clonal deletion”.

“(It) is the process by which the developing immune cells in a fetus are presented with small bits of chewed-up proteins from the fetus’s own body. The immune cells that react to those bits of self-protein are then eliminated; they are “deleted” from the immune system.”

 

Step 2 is messy: it happens after birth. At birth, the baby finds itself bombarded by a zillion things it has never experienced before:

“(The immune system) has to learn who is friend and who is foe.”

Initially, it adopts a “wait and see” approach. Do nothing when faced with a foreign particle; wait and see if an infection starts to develop!

“If it does, it’s time to kick things into high gear; if it doesn’t, the foreigner is seen as no big deal.”

Within the first few years of life, the immune system “starts to settle into a mature state, assuming that it has seen most of the harmless stuff by then”.

 

You might have guessed what then cause allergies to commonplace things, like peanuts. While not proven yet, it is generally believed that the sharp rise of severe allergies in the West are due to extreme hygiene in recent decades. Ironically, by sanitizing everything around themselves and even more so around their babies, the West may have deprived the baby’s immune system from a “normal” Step 2.

 

All of which is probably the basis for Lent’s punchline on all immune system related problems:

“We have met the enemy, and it is us.”