Philipp Dettmer, Immune: A Journey into the Mysterious System That Keeps You Alive, New York, Random House,  2021, 341 pages, Hardcover, $21.99 (K372.70)

Philipp Dettmer, Immune: A Journey into the Mysterious System That Keeps You Alive, New York, Random House,  2021, 341 pages, Hardcover, $21.99 (K372.70)



Mwizenge S. Tembo, Ph. D

Emeritus Professor of Sociology


You own a large three-bedroom house. In the kitchen you have mealie-meal, cooking oil, bananas, oranges, onion, bread, biscuits, and tomato to last the whole month. You have a fridge full of raw and cooked food, all kinds of soft drinks including a crate of beer. You have a large screen cable TV  with over two hundred stations in your very comfortable living room with thick sofas. Your bedrooms have good beds with thick comfortable mattresses with good blankets. The closets are full of the latest new clothes and shoes. The shower has good soap and your flash toilet is clean. The house has two doors, ten windows, a ceiling and a roof.

As you are sitting in the living room flipping channels watching TV, you look out of the window. There are hundreds of robbers all around your house every night and day who want to find ways to break into your house, kill you and your family so that they can settle in, eat, enjoy themselves, steal, occupy, live in and take over your house. The house is your body, you, and your family and relatives living happily inside it. The fierce armed robbers who are all around outside the house walls, doors, windows, and roof banging and trying to  invade and get into your body are the numerous germs or enemies outside your body, that create havoc through disease, illness, and death trying to get into your body to kill you. How does all of this relate to your life and 7.7 billion other human beings in the world which include 17 million Zambians?

Immune: the Book.


Philipp Dettmer has published a book “Immune: A Journey into the Mysterious System That Keeps You Alive” in which he describes in the most understandable way how the immune system operates to defend your body and mine in 45 short chapters. The chapters include: The Empires and Kingdoms of the immune system; Naked, Blind, and Afraid: How Do Cells Know Where to Go?; Weapon Factories and Sniper Rifles: B Cells and Antibodies; How a Viral Infection is Eradicated; When Your Immune System is Too Weak: HIV and AIDS; The Hygiene Hypothesis and Old Friends.

We can walk, laugh, work, eat, play, read, have sex, go to school to earn certificates, diplomas, degrees, and do many things that make us happy because the immune system keeps us safe from germs. But what is surprising is that the body and the immune defensive system are both very complex and complicated. This is why despite advances in science, some of the activities of the body and the germs are still not well understood.

Dettmer first describes the physiology of the body, who are the soldiers that defend our bodies against our enemies both inside and outside our bodies, how do the soldiers defend our bodies, and what happens when our valiant soldiers lose the war to the invading enemies in form of germs?

Our bodies are very big. They range for an adult in height from 5ft or 1.52 meters to 7ft or 2.13 meters. Our adult bodies can weigh ranging from 130lbs or 58.9kg to 300lbs or 136.07kg. The body is composed of flesh and muscles, 60% water, and fluids such as blood that the heart pumps through veins making the fluids flow throughout our body. The body is protected from enemies outside our bodies with a thick skin that has a surface area of 2 square yards or 1.67square meters. According to Dettmer, the skin “luckily is not that hard to defend, since most of it is made out of a hard and thick barrier covered with its own defense system. It feels soft, but is pretty hard to breach if it is intact.” (p.11)

In the house example that was used earlier, robbers,  burglars, and enemies are likely to pry doors and windows to try to enter your house to attack you.  Similarly, the weakest points that germs are likely to enter to attack your body are the openings in your body which are your mucous membranes. According to Dettmer, these are “the surface that lines your windpipe and lungs, eyelids, mouth, and nose, your stomach and intestines, your reproductive tracts and bladder….on average there are about 200 square yards or 167.22 sq. meters of mucous membrane….the size of tennis court.” (p.11)

What is the unit that defends our body in the immune system? The smallest unit that the immune system is built around is the cell.  The cell is a very tiny microscopic unit compared to our huge body. But the cell does numerous things for our body. The tiny cell has so many things in it and performs so many functions. According to Dettmer, inside the cell there is a nucleus, “….the information center of your cell – pretty large structure with its own protective border wall that houses your DNA, your genetic code.” (p. 17)  The cell’s insides has millions of molecules and proteins. Proteins are the most important building blocks and tools for not only our bodies but all living things.

The body has forty trillion cells including red blood cells, muscle cells, fat cells, epithelial cells, and immune cells, just to mention a few (p.13). The numerous immune cells include the Dendric Cell, Natural Killer Cell, T-Cell. B Cell. Mast Cell, Macrophage, Antibodies, Basophil, and Eosinophil (p.28).  You name anything in the human body there is a cell for it. How does the immune system operate to defend the body using the Innate Immune System and the Adaptive Immune System? Who are the sworn enemies of the body that if they manage to get into our bodies, we may become very sick or even die?

The three major microorganisms that are enemies that are always threatening our bodies are parasites such as bacteria, viruses, and others. The total number of bacteria in the whole world is estimated to be 5,000,000,000,000,000,000,000,000,000,000. This is five million trillion trillion or 5 x 10 to the 30th power. Because they are so ubiquitous, they are everywhere and we can never get rid of them. However not all bacteria are enemies to the human body. Since about 3.5 billion years ago (p.3) when the human immune system began to evolve, some bacteria are hostile but others are friendly and actually live inside our bodies and help us to live a healthy life. For example, according to Dettmer, around your intestines, “ ……on your gut mucosa, around thirty to forty trillion individual bacteria from around 1,000 different species and tens of thousands of species of viruses make up your gut microbiota” (p.162). There are one million bacteria on a square centimeter of your skin alone (p.45). The difficult job of the immune system is to keep the friendly bacteria but kill the dangerous bacteria. There are also an estimated ten thousand billion, billion, billion viruses. (p.168)

This information about your immune system should not scare you. Instead, it should create a better understanding of what it takes for us to live healthy lives every day. Often, we are not even aware of the internal battles our immune system fights every single day. But even more important, this information should help us understand how and why we get sick and sometimes die. Why do we have malaria fever, influenza epidemics during the cold or winter months, cholera, childhood diarrhea kills millions of children, HIV/AIDS, Ebola, and now the Corona Virus or Corvid 19? Instead of paying attention to conspiracy theories, what do vaccines do? How can we help our bodies strengthen our immune system beyond taking drugs?

I highly recommend this book for the ordinary reader, teachers of introduction to biology and the immune system, nurses, students in all medical fields, and students of the relationship between evolutionary biology, diseases, and pandemics.