Modern Medical Laboratory Journal

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. In a recent study, the researchers estimated the abundance of the primary immune cell types throughout all tissues in the human body. They conducted a literature survey and integrated data from multiplexed imaging and methylome-based deconvolution. They also considered cellular mass to determine the distribution of immune cells in terms of both number and total mass. Their 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.
Read more