Immune A Journey into the Mysterious System That Keeps You Alive

Our lives depend on a functioning immune system, but few of us understand how it works and fewer still can explain it. Thus, Philip Dettmer, the creator of the wildly successful popular science YouTube channel Kurzegsagt, has written this chunky book. An entertaining crash course in immunobiology, it does a wonderful job at introducing all the moving parts that make up this byzantine system.

Dettmer's interest in this topic started in university while studying information design. Innocently thinking that reading up on the immune system would make for a nice semester project, it has kept him fascinated for nearly a decade. Meanwhile, Kurzgesagt took off and became a full-time occupation. Some topics, however, do not lend themselves well to short, ten-minute videos; immunology and its jargon befuddle even specialists. Thus Dettmer's decision to write a book. Before diving in, it might be worth pointing out that this is not a graphic novel or art book. This is popular science writing that is nicely complemented by Philip Laibacher's drawings that ooze the signature Kurzgesagt style.

Drawing on the textbook Janeway's Immunobiology, review papers, technical articles, and feedback and help from three immunologists, Immune introduces the inner workings of the human immune system. In essence, it is a tool to distinguish and protect the self from the other. Behind that simple statement hides a world of complexity. To keep it accessible and interesting to a lay audience, Dettmer mentions that he simplifies the material and is selective about the level of detail he includes. He is similarly upfront about the stylistic choice to anthropomorphise and assign agency to processes that are basically mindless biochemistry. And he reminds readers of this in various places in the book when introducing delightful details in footnotes, or highlighting areas where immunologists disagree over the best interpretation.

What follows is an excellently structured book divided into 45 short chapters of two to ten pages each that is a real eye-opener. Dettmer walks you through a typical bacterial infection after you step on a sharp nail, and a viral infection after you catch the flu. As he follows these processes, he regularly pauses the playback, so to speak, to introduce all the major cell types of both your innate and adaptive immune system, and the central role of your lymphatic system where information is relayed from one to the other. Coming out at the other end you will better understand what each of these cells does, how they differ, and how they interact. A final part discusses examples of the immune system malfunctioning, such as autoimmune diseases, allergies, and cancer.

Let me give you one example of the awe-inspiring details I learned about. Except for red blood cells, all your cells have NHC class I proteins embedded in their membrane. They act as a sort of display windows that bind random internal proteins, essentially presenting a snapshot of a cell's biochemistry to the outside world. Who monitors these display windows? Killer T cells do. Once activated by an infection (you will learn all about the cascade that leads to this), they move through the body inspecting MHC class I molecules on cells. If they detect that a cell's biochemistry is compromised by an invader, they will order that cell to destroy itself. Now for the interesting bit. Some viruses have evolved the ability to order a cell to stop making MHC class I. Without display windows, these infected cells effectively become invisible to your immune system. In turn, the body has evolved a counter-response: natural killer cells. These are always "on", ready to kill, and only the presence of MHC class I stops them from doing so. This offers an effective way of sniffing out rogue cells. How neat is that?

More important than interesting trivia is that Immune brilliantly reveals the bigger picture of how your immune system works. First, it relies on constant positive reinforcement. This feedback mechanism ensures that immune responses fizzle out as infections are overcome without the need for a central command structure. Second, your immune system is constantly balanced between suppressing infections in a timely fashion, but not being so aggressive that it injures you. It has incredibly powerful weapons at its disposal that can kill you in minutes, so it requires checks, balances, and the biochemical equivalent of two-factor authentication before unleashing its full potential. Most discomfort you experience during an infection are side-effects of your immune system in action, not of the pathogen.

There are two other noticeable facets to this book. First, Dettmer is outspoken in his criticism. This was music to my ears but might challenge the beliefs of some readers. He criticizes "people who don't understand chemistry" (p. 239) and claim the adjuvants added to vaccines are a poison. In reality, they activate the immune response for those vaccines that are otherwise too harmless. He criticizes the anti-vaxxers who wilfully expose their children to measles by highlighting that it kills immunological memory cells. A case of what does not kill you makes you weaker. He criticizes the wellness gurus who spread the discredited idea that a positive attitude "will activate some mystical force in the immune system and enable it to overcome [cancer]" (p. 292). A horrible notion that effectively blames the sick for failing to get better. Foremost, he criticizes the supplement industry for peddling the idea that you can boost your immune system. By the time you finish the book, you understand that the immune system is a balancing act. Boosting it "is a horrible idea that is used by people trying to make you buy useless stuff!" (p. 280), and success would risk autoimmune diseases, chronic inflammation, or allergies.

The other facet is that some of Dettmer's metaphors are rather violent and graphical. For example, there is a strict selection process during T cell training to prevent them from treating your cells as foreign intruders. T cells that fail to pass this test are ordered to undergo programmed cell death. Dettmer describes it as teachers shooting their students in the face. Wait, what? Probably intended to make the writing more engaging, his off-beat jokes got some chuckles out of me but will definitely not appeal to everyone. I am a tad surprised at their inclusion in a book that is so clearly aimed at a very broad audience.

In a nutshell, Immune is an everyman's immunology textbook. It introduces the major players involved while illuminating the overall mechanism by which our immune system functions. This is a highly recommended starting point that will equip you with the basic knowledge you need to read deeper into this challenging topic.