The Total Mass, Number, and Distribution of Immune Cells in the Human Body | Virus World | Scoop.it
From www.pnas.org - October 25, 2023 1:24 PM
We characterized the human body’s immune cells distribution and provided its total weight. Our findings show that an average individual’s immune system consists of approximately 1.8 trillion cells, weighing around 1.2 kg. Lymphocytes make up 40% of the total number of immune cells and 15% of their mass. Similarly, neutrophils account for comparable proportions. Notably, macrophages constitute 10% of immune cells but contribute nearly 50% of the total cellular mass due to their large size. This knowledge gives an integrative quantitative view of the immune system and facilitates the development of models.
 
The immune system is a complex network of cells with critical functions in health and disease. However, a comprehensive census of the cells comprising the immune system is lacking. Here, we estimated the abundance of the primary immune cell types throughout all tissues in the human body. We conducted a literature survey and integrated data from multiplexed imaging and methylome-based deconvolution. We also considered cellular mass to determine the distribution of immune cells in terms of both number and total mass. Our results indicate that the immune system of a reference 73 kg man consists of 1.8 × 1012 cells (95% CI 1.5–2.3 × 1012), weighing 1.2 kg (95% CI 0.8–1.9). Lymphocytes constitute 40% of the total number of immune cells and 15% of the mass and are mainly located in the lymph nodes and spleen. Neutrophils account for similar proportions of both the number and total mass of immune cells, with most neutrophils residing in the bone marrow. Macrophages, present in most tissues, account for 10% of immune cells but contribute nearly 50% of the total cellular mass due to their large size. The quantification of immune cells within the human body presented here can serve to understand the immune function better and facilitate quantitative modeling of this vital system.
 
Published in PNAS (October 23, 2023):