The podcast explores the total mass and number of immune cells in the human body, as well as the size and weight of organs. It discusses the differences in immune cell density between blood and organs, and analyzes the distribution and abundance of immune cells. The hosts also discuss the potential influence of Duplimumab on COVID-19 severity and delve into the role of mast cells and allergies.
Macrophages contribute nearly 50% of the total cellular mass in the human body.
The lymphatic system and bone marrow have the highest number of immune cells, while blood has lower immune cell density.
Mast cells, traditionally associated with allergies, may have important physiological functions and type 2 immune responses can have beneficial effects in certain infections.
Deep dives
Total number and distribution of immune cells in the human body
This podcast episode discusses a recent study that explores the total number and distribution of immune cells in the human body. The study calculates that there are approximately 37 trillion cells in the body, with 1.5 trillion of those being immune cells. Neutrophils are the most abundant immune cells, followed by T cells, B cells, and macrophages. The study also examines the density and distribution of immune cells in various organs, with the lymphatic system and bone marrow having the highest immune cell density.
Weight of immune cells and organs
The podcast episode highlights the weight of immune cells and organs in the body. Macrophages are the heaviest immune cells, weighing more than any other cell type. The total weight of macrophages in the body is approximately 600 grams. Neutrophils are the most numerous immune cells and have a total weight of around 300 grams. The lymphatic system and bone marrow are the heaviest immune organs, with the bone marrow weighing 400 grams and the lymphatic system weighing 300 grams.
Impact of age and tissue types on the immune system
The episode also touches on the impact of age and tissue types on the immune system. The study finds that the bone marrow and lymphatic system are the largest immune organs, while adipose tissue has the lowest immune cell density. Additionally, the study notes that the cellularity of the bone marrow can decrease by up to 40% in older individuals, leading to a reduction in the total number of immune cells. The episode concludes by highlighting the importance of understanding the distribution and weight of immune cells in relation to overall health and immune function.
Implications of immune cell density in different tissues
This podcast episode discusses the distribution and density of immune cells in various tissues. The researchers found that the lymphatic system and bone marrow have the highest number of immune cells, accounting for the majority of the immune cell population in the body. Blood, in contrast, has a different profile with lower immune cell density. The study also highlighted the diverse composition of immune cells in different tissues, such as lymphocytes in the lymphatic system and neutrophils in the bone marrow. The significance of these findings in different disease states and conditions is yet to be explored.
The potential role of mast cells and type 2 responses
The episode touched upon the presence of mast cells in various tissues, such as the gut, skin, and lung. Mast cells, traditionally associated with allergies and pathology, were found to be present in significant numbers. This suggests that mast cells may have important physiological functions. Additionally, the podcast discussed the potential protective role of type 2 immune responses in conditions like sepsis and pneumonia. The activation of type 2 responses was associated with improved outcomes in these infections. These findings challenge previous assumptions about the detrimental nature of type 2 responses and highlight their potential beneficial effects.
Immune reveals the total mass (1.2kg), number (1.8 trillion), and distribution of immune cells in the human body, with macrophages contributing nearly 50% of the total cellular mass.
