“Imagine you would go through the day, minding your business, and suddenly hundreds of thousands of flies covered your skin. This would be a horrifying experience, and for a bacterium, this process can cripple and maim. And now imagine the flies turning into wasps in the blink of an eye. Another cascade is about to begin. This one will be deadly.”

This is not a paragraph out of some horror novel, but the words Philipp Dettmer uses to explain the concept of harmful bacteria being tackled by Compliment, a key player in the human immune system.

The book ‘Immune’, 315 pages long and beautifully illustrated, provides a unique introduction into the intricacies of the subject.

Simplifying a formidable subject

As the pandemic enters its third year, interest in immunology has spiked. Immunology jargon has become part of everyday vocabulary - particularly on television news channels as well as other media. This book, written in plain English, is arriving at the right time.


Even for a medical doctor who spends no less than 5 1/2 years learning about the human body and disease, immunology remains a formidable subject. While communicating science, I often equate the human immune system to the chessboard, where each player has specific roles, strengths and limitations - and no single player is able to win or lose the game on their own.

Philipp Dettmer’s book, although simplified to the extent possible, will take patient reading - especially for those who are not adept at immunology. The author introduces the topic slowly, and the initial chapters helpfully include a primer on cell biology and evolution of the immune system.

“Sadly, when your immune system under- or overcommits, death or suffering are the consequences”, writes Dettmer, highlighting the double-edged trait of its powerful components. In the last chapter, he makes an important comment about people attempting to “boost their immune systems”, frequently duped by advertisements into purchasing supplements that have no scientific merit. The truth is, unlike our muscle mass or vocabulary, immunity is not a commodity that can be boosted.

The initial few chapters make slow reading for someone who is already familiar with the topic and could even be skipped until chapter 7, when Dettmer describes a stroll through the woods on a pleasant summer day, when a cut wound occurs on our big toe. Using this basic template, he introduces the multiple players of the human immune system in the subsequent chapters. This experiment successfully holds the narrative together. Context is important in comprehending the role of each component in the multi-level immunity game.

The metaphor of a battlefield

Reminiscent of epic war movies, Dettmer describes a raging battle scene where the first respondents are tired and rapidly losing heart. Chapter 15 describes how the macrophages (Dettmer calls them black rhinos) are exhausted, and almost defeated.


“Suddenly thousands of new soldiers arrive, which are the T helper cells. A jolt of energy shoots through the macrophage’s bloated body. In a heartbeat, its spirit comes back and it feels fresh again. Helper T cells whisper magic words to the tired soldiers, motivating them to get themselves together and engage the bacteria again - with even more violence than before. The specialist forces of antibodies then arrive, like assassins with sniper rifles”

By using the metaphor of a battlefield in reference to the big toe wound, Dettmer is able to connect multiple players of the immune system in sequence. The intervening chapters explain the role of each component - with easy examples and diagrams.

Anyone who is curious to understand the human immune system and is willing to invest the time for it, must get hold of this book. Some chapters will require to be read again, as it would be laborious to finish this book in one sitting.

The idea of introducing each player separately in chapters is thoughtful. Dettmer describes the dendritic cell as an “intelligence officer”, while he chooses to call a neutrophil “a chimp on Coke with a bad temper and a machine gun”. As people with teaching experience would admit, complex concepts and interactions are best explained using such metaphors, which are liberally used throughout the text. Helpful summaries are provided at various points.

The book could mean different things to people of different levels of knowledge. ‘Immune’ would be a handy assistant for medical students, doctors and science enthusiasts who wish to master the topic. They will find Dettmer’s style refreshing, especially after being used to the subject being presented in a monotonous format in medical textbooks. For someone who is curious to understand the immune system, it is a must-read. Experts in biology could skip to their chapters of interest.

Although not a medical doctor or an immunologist, Dettmer has studied the topic in detail and consulted experts in the field while creating this book. Towards the end, he has included a basic introduction to certain conditions such as cancer, allergies, autoimmune disease and COVID-19. This section is not only of practical relevance, but also allows readers to apply some of the concepts acquired while reading the prior chapters. Metaphorically, this section might make the reader feel like an enthusiastic medical student being taken for the first ward round - after spending a few years learning basic sciences.

(Dr Rajeev Jayadevan is a specialist physician, public educator, author and is a member of the National Task Force of IMA for Coronavirus pandemic)

About the Book

‘Immune’: A Journey into the Mysterious System That Keeps You Alive 

Philip Dettmer 

Hodder & Stoughton

Rs 949 (hardcover); 368 pages

Check this book out on Amazon