A person’s immune system can weigh between 1 to 1.2 kilograms and contain approximately 1.8 trillion cells, according to research conducted at the Weizmann Institute of Science in Israel.
The immune system is a complex system made up of different types of cells with important functions. For example, lymphocytes are a type of white blood cell that produce antibodies to combat viruses and other pathogens. Mast cells, another component of the immune system, regulate the body’s inflammatory response to injury.
To gain a deeper understanding of the composition of the immune system, scientist Ron Milo and his team conducted a comprehensive study of its cells. They estimated the number of immune cells in different tissues based on previous research and analyzed samples from individuals of various ages and genders.
The findings revealed that a 73-kilogram man between the ages of 20 and 30 has around 1.8 trillion immune cells, weighing approximately 1.2 kilograms. Similarly, a 60-kilogram woman of the same age has 1.5 trillion immune cells, weighing 1 kilogram. The number of cells decreases to 1 trillion for a 10-year-old child, with the immune system weighing around 0.6 kilograms.
Regardless of age or gender, lymphocytes and neutrophils make up 40% of all immune cells and contribute to 15% of the immune system’s total mass. These cells are predominantly found in the bone marrow, lymph nodes, and the spleen. Macrophages, which are responsible for engulfing pathogens, are the largest immune cells and contribute nearly half of the immune system’s total mass, despite only comprising 10% of the cells.
Understanding the immune system in this detailed manner can provide valuable insights into how our bodies defend against infections and various medical conditions. It can also aid in the development of quantitative infection models and contribute to the advancement of effective clinical treatments.
