How many are immune cells?

how many are immune cells

The number of cells in my body is 30 trillion. Among them, how many are immune cells?

As our interest in aging increases, interest in the most basic cells in the body also increases.
In particular, the importance of immunity and immune cells is emphasized, and recent research results have answered the question of how many immune cells.

The number of immune cells is 1.8 trillion in men, 1.5 trillion in women, and 1 trillion in children.

Professor Ron Milo’s team at the Weizmann Institute of Science in Israel analyzed the results of immune cell research published so far through Google Scholar and Public Med searches, and found that the human immune system consists of approximately 30 trillion cells out of the total number of cells. It is composed of approximately 1.8 trillion cells (based on an adult male weighing 73 kg), and the total weight is estimated to be approximately 1.2 kg, according to the Proceedings of the National Academy of Sciences (PNAS). For women, it is 1.1 trillion per 60 kg of body weight, and for children, it is per 10 kg of body weight.
Professor Milo’s team is a notable research team that publishes research that quantitatively analyzes cells in the human body.
As an estimate, in 2016, the number of cells in the human body was 30 trillion and the number of bacteria was 38 trillion, and in 2021, the results of cell turnover analysis were announced that our body replaces an average of about 330 billion cells per day. there is.
Based on Professor Millo’s team’s cell estimates, the number of immune cells corresponds to 6% of the total number of cells, and the mass corresponds to approximately 2% of the total. 1.2kg is roughly similar to the weight of one pineapple. The study of immune cells is the result of their third cell quantification effort.

The number of immune cells is 1.8 trillion in men, 1.5 trillion in women, and 1 trillion in children.

One of the biggest concerns of immunologists is which organ in the human body contains the most immune cells. Studies have shown that most human immune cells reside in the lymphatic system and bone marrow. Among these, there are 760 billion lymphocytes, mainly distributed in the lymph nodes and spleen, accounting for 40% of the number of immune cells.
Lymphocytes are the smallest cell group, making up only 15% (200 g) by mass.

  • T cells: 60% – Directly attack pathogens
  • B cells: 33% – Cells that produce antibodies
  • Natural killer (NK) cells
  • Plasma cells

The number of macrophages is small, but because they are large in size, they weigh a lot and are said to occupy 600g, or 50% of the total mass.
Immune cells weigh hundreds of picograms (one picogram = one trillionth of a gram), while macrophages are much larger, weighing a few nanograms (one nanogram = one billionth of a gram).

Immune cells in your body play a very important role. If you are curious about the role of each immune cell, learn more.

※ Reference : The total mass, number, and distribution of immune cells in the human body (

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