Most people do not know that the thymus is the most important organ of the immune system during infancy and early childhood, years before any other lymphoid organ has had a chance to become active.
More than just an explanation of how your immune system works, this article is filled with practical tips on how you can boost your immunity and avoid getting sick. There’s also common myths about our body’s defenses we would like to dispel. Discover more about where you can find bone marrow and why it plays such a critical role in transplant patients. And finally, we’ll close with some ideas about what factors contribute to triggering depression.
Because we have included both text and images, you can also use this article as a handy reference. Simply open it to any section and become an instant expert on life-saving information about your immune system and its organs.
Which lymphoid organ is primarily active during the early years of life?
The thymus is the major lymphoid organ during early life and is responsible for producing T lymphocytes. The thymus begins to fade away shortly before puberty and becomes almost non-functional after age 17.
The spleen, however, does not fully mature until adulthood. The spleen is also part of the lymphatic system and helps filter out foreign matter from the body. It also produces lymphocytes, including B cells that produce antibodies, which help you fight off infections.
Although the bone marrow plays a minor role in immunity when compared to other organs during early life, its function increases over time as it produces both white blood cells and platelets that help your blood clot in case of injury or bleeding.
How does your immune system work?
During the first few years of life, a large amount of your body’s resources are spent on creating and protecting the many organs that make up your immune system. In fact, at least half of the cells in your body are literally the hard-working immune cells that form immunologic organs such as lymph nodes, tonsils and bone marrow .
Bone Marrow: Where New Immune System Cells Are Created
The spongy bone marrow inside bones is made up of a matrix of thin, branching channels through which blood flows. It is the primary site of blood cell generation (hematopoiesis). In fact, it is the only organ that continuously produces new blood cells throughout life.
During early childhood, almost all the cells produced in the bone marrow are lymphocytes. However, as you get older, your bone marrow begins to produce red blood cells and platelets. As a result, you can feel tired when your body’s supply of new immune cells is low.
The Bone Marrow From A Patient Waiting For A Transplant
A number of tissues in your body contain many stem cells. These are cells that can develop into many different types of cells. Stem cells from the bone marrow are often used to treat patients with leukemia, lymphoma, aplastic anemia and other blood disorders.
Before being able to use stem cells from the bone marrow, you must first receive chemotherapy that destroys cancerous blood cells. The stem cells are then removed from your bone marrow and frozen in liquid nitrogen for later use.
Why does your body need bone marrow?
Bear in mind that transplants using your own stem cells have a better chance of success than transplants using stem cells collected from another person (allogeneic).
Production of new blood cells in a healthy person begins with a decision made by your doctor. He makes this decision based on the type of leukemia you have and how severe it is. For example, if you were found to have a severe illness such as acute lymphocytic leukemia (ALL), then your doctor would harvest bone marrow from your hip bone.
The bone marrow from an ALL patient awaiting a transplant (below) has been cryopreserved for later use. This cold-storage method (also known as ‘dry freezing’) preserves the patients’ bone marrow for future use.
The bone marrow is removed from the patient and stored in liquid nitrogen until it can be transplanted into a patient with a different type of leukemia. At that time, the extracted cells are thawed, expanded and reinjected into the patient’s body.
The life cycle of blood cells. The blue line represents your blood cells’ journey through your body. They start by taking on a specific shape (called “maturation”) in the bone marrow before infiltrating other tissues throughout your body and entering into circulation.
Bone marrow and stem cells
The type of blood cell that is produced in your bone marrow depends on the kind of blood cell that you need. For example, your immune system requires B lymphocytes to fight certain types of bacteria and viruses. Your red blood cells are made from stem cells in the bone marrow.
