Imagine you find an alien spacecraft crashed in your backyard. A door has cracked open. You carefully step inside. You discover a world beyond your comprehension. Objects appear before your eyes, only to disappear into thin air. Lights flash in colors you cannot see. It will take humanity’s brightest minds years—decades—to make sense of it all.

Biology is a science attempting to comprehend something no less strange or bizarre: the evolved nano-machinery that constitutes what we call life. We give our discoveries opaque names. Ribosomes. The Golgi apparatus. Neutrophils. When those get too long, we abbreviate. MHC class I and II. ACE2. CD24.

Here lies a wondrous and endlessly fascinating world. Understanding it better could enrich our lives and help immunize us against dangerous pseudoscience. If only we were better at describing this complex, seemingly impenetrable universe inside our own bodies!

Philipp Dettmer is no stranger to making the complex comprehensible. He founded a YouTube channel called Kurzgesagt (“in a nutshell”), which publishes lovingly crafted videos on subjects like wormholes, geoengineering, and brain-eating amoebas. Thanks to brilliant animation, epic music and a dark sense of humor, every video is a treat.

Immune: A Journey into the Mysterious System That Keeps You Alive is Dettmer’s first attempt to bring Kurzgesagt’s trademark educational approach into book form. On 341 pages, Immune sheds light on the incredibly complex macromolecular machinery that protects us against bacteria, viruses, and even snake venom and parasitic worms.

Most illustrations are more understated than the ones shown here, but this is not a book that shies away from depicting a Kiler T Cell saying “BLARGHL”. (Credit: Philipp Dettmer / Random House. Fair use.)

This is not a textbook. Nor is it the kind of pop science writing that tries to make science accessible by giving you lots of biographical detail about scientists. It’s strictly focused on the actual mechanics of the immune system, but written in a style that’s entirely Dettmer’s own. To give a small sample:

The Neutrophil is a bit of a simpler fellow. It exists to fight and to die for the collective. It is the crazy suicidal Spartan warrior of the immune system. Or if you want to stay in the animal kingdom, a chimp on coke with a bad temper and a machine gun. [p. 59]

Of course, Dettmer frequently reminds us that the immune system is not, in fact, sentient or intentional. It’s just that these kinds of analogies are too darn useful to refrain from using them. So, Dettmer talks about hot dog buns, display windows, and desert kingdoms as he helps us navigate the complex nano-scale landscape inside our bodies.

But analogies only go so far, and the book uses biological terms and plenty of straightforward illustrations. At the same time, Dettmer will often (a bit too often) emphasize that he’s still simplifying things greatly. The book is littered with entertaining footnotes that expand on the text.

Cells with two-factor authentication

The immune systems of humans and other animals don’t just have to kill invaders. They have to adapt to viruses they’ve never encountered before, detect cells that have been hijacked, calm down when a threat has been eliminated. To make matters worse, the attackers evolve rapidly!

Immune responses involve the innate immune system, a sort of standing army, and the adaptive immune system, which crafts specialized responses for novel threats. Together, they self-organize into a complex dance. Isolate the threat. Sample data. Ramp up immune responses. Kill or neutralize invaders. Detect cells that behave suspiciously. Mess with virus production.

Perhaps most fascinating is our bodies’ ability to learn and remember—to acquire immunity. At its heart is what Dettmer calls the largest library in the universe: T-cells. Wikipedia has a more understated but no less awe-inspiring description:

Each mature T cell will ultimately contain a unique T-cell receptor that reacts to a random pattern, allowing the immune system to recognize many different types of pathogens. This process is essential in developing immunity to threats that the immune system has not encountered before, since due to random variation there will always be at least one TCR to match any new pathogen.

It takes time for our adaptive immune system to find the perfect match for any given threat. But once it has done so, it switches into a kind of mass-production mode, to produce vast numbers of antibodies tailored to a specific enemy.

To avoid misfiring, cells perform complex verification dances. T-cells undergo a selection process that weeds out ones that might attack the body. And they must be matched with another cell type (B-cells) that have been activated by the same threat. Dettmer calls it a kind of two-factor authentication.

As someone working a lot with technology, I found these comparisons illuminating. Understanding the sophisticated evolved security responses of our bodies may very well inspire us to develop better ways to deal with novel threats of a more digital variety.

Knowledge as immunity

Our brain, in a way, is part of our immune response. Our decisions on what to eat and drink, what to do with our free time, how to prevent and how to treat illness—they profoundly influence our ability to stay healthy, and to get better. When we believe things that are patently false, it can literally kill us.

Dettmer spends the final sections of his book trying to convey how understanding our immune system can help us make better decisions.

He explains the remarkable accomplishment of vaccination as a way to train the body without hurting it: like a dojo where you learn to fight with weapons made of foam and paper. In contrast, parents who opt their kids out of vaccines are sending them to a “Nature Dojo”:

The philosophy of the head trainer is that kids should train with real weapons, real knives and swords, so they are better prepared for the real dangers of the world. After all, it is more natural and real life just is dangerous. From time to time, a student will get a deep cut and require stitches. And yeah, OK, there may be a lost eye and sometimes a kid may die. But it is the natural way! [p. 240]

He asks us to question dubious claims about “boosting your immunity”—reminding us of the immune system’s mind-boggling complexity and interplay of countless parts, where any actually effective intervention can have disastrous effects. He tells us to exercise (it’s obligatory in any book of this kind), and describes how stress can knock our immune system out of balance.

These final sections of the book sometimes get a bit rambling. The most muddled chapter discusses the popular misconception that hygiene has weakened our immunity against disease. Dettmer argues for preserving good hygiene while also embracing the role of nature and dirt in our lives—a reasonable argument that’s unfortunately not very coherently made.

The Verdict

With Immune, Dettmer has managed something very difficult: to write a long book almost entirely about the mind-boggling macromolecular and cellular machinery inside our bodies, without fluff, that’s entertaining to read. I would love to read similar books about subjects like epigenetics, metabolic pathways, or neurobiology!

Science books often have an incongruous approach to visual explanation. Immune is the rare exception—while it does not have as many illustrations as some readers might expect from the Kurzgesagt founder, what’s here supports the text perfectly in a consistent, pleasing style.

The latter parts of the book would have benefited from a bit more rigorous editing, but I’m glad that Dettmer’s funny and casual voice hasn’t been whittled down to science-journalism-speak.

All in all, I cannot recommend the book highly enough, and would give it a full 5 stars.