Immune System and Boundary

2020, Jul 27    

The phospholipid bilayer is a massive innovation in biology that made life as we know it possible. The layer has two key components: a hydrophilic (water-loving) part (phospho-) and a hydrophobic (water-hating) part (-lipid).

Lipids are just fats, oils. As anyone who has seen a bowl of ramen or a puddle of rain on the side of a road can tell you - lipids reject water. Perhaps more importantly, they stick to each other. These fats bond pairwise with each other and then chain together, creating a thin sheet. If you’re really lucky, they form a little bubble that you can see on the surface of the water. Turns out, we’re all descended from what amount to little oil bubbles. The chemistry of the phospholipid bilayer proffers a particular advantage - oil bubbles have to be air inside, they cannot hold water. A phospholipid bilayer can.

This is the very first boundary that we would recognize in biology. There is an inside and an outside, which allows things to grow on the inside which are vulnerable to outside forces during their nascent stage. The boundary also allows for a different environment inside, one that removes elements of the outside that are noxious to the things we want to grow within. The mechanism responsible for this is the immune system.

A country is defined partially by its boundary with others. The immune system of a nation consists of several layers of police, but also cultural norms and prejudices that keep foreign ideas and people from integrating into the system without shaving off their threatening aspects. Sometimes foreign bodies can be fully taken in and coopted to become a part of the system. In the biological metaphor, the mitochondria was originally another organism entirely that was engulfed by a larger one and forced to become the powerhouse of the cell. This is why mitochondrial DNA offers different and interesting clues about one’s origins - it’s passed only maternally.

The common immune response to intruders is a high fever. The response itself is driven by sound biology - invaders are usually not able to survive higher temperatures. In a country, perhaps that amounts to something like a massive security lockdown to try to catch terrorists. It’s seizing up the whole body to attempt to pull out the impurities. Nowadays, we fight our own body’s immune over-responses as much as we fight disease. Coronavirus seems to trigger a cytokine release which is what ultimately inflames your body and causes system failure.

But what if it’s your psyche? What is the boundary on what you let into your psyche and how do you trigger an immune response to infiltration? How do you know what an over-response is?

I’ve been trying to map out how things enter my mind, what is an acceptable port of entry for me. I used to find the world to be a torrent of information I couldn’t turn off. Every moment was gigabytes of data being downloaded, and I could scarcely store it all, much less process it. At some point during lockdown, I entered into a state of harmony with my own thoughts. The only things entering my room were food, voices of the people I love - friends, family - and the internet. My mind became incredibly peaceful. There was no immune response, no angst I had to quell.

I used to take an aspirin before parties or social gatherings. Turns out, it’s a well-known cure for social anxiety. The gap between the mind’s immune response and the body’s seems to be practically nothing for me. An inflammation of the body due to a lack of exercise, too much milk or fitful sleep results in a day of inflamed thoughts and moody touchiness.

Perhaps my boundary walls grew so high during lockdown my immune system forgot how to moderate people and ideas. More likely, I never knew. And I never had boundary walls either.