The Spleen—Largest Lymphatic Organ in the Body

Larry A. Law

The spleen is one of the least understood organs in the body. It is part of the lymphatic system. The lymphatic system is the garbage processing/recycling function in the body and the spleen is the largest organ belonging to that arena. The spleen resembles one of your kidneys. It is fist sized and it sits next to the stomach on the left side of your body. It is made up of two types of tissues: red pulp, which contains red blood cells; and white pulp, which contains white blood cells. The spleen sits like a reservoir in the circulatory system. It removes old blood cells and filters the blood to remove pathogens and encapsulated germs (bacteria that are double-protected and more resistant to the body's immunity). In addition, it regulates immune defense functions and produces antibodies. 

Spleen's Three Primary Functions 

1. Producing and Recycling Red Blood Cells

During the first weeks of a baby's development in the womb (weeks 12 to 28), the spleen produces most of the red blood cells (RBCs). After week 28, the bone marrow takes over. RBCs only last 4 months in circulation before they wear out and need to be replaced. Macrophages engulf about 5 million red blood cells every second. Blood flows through the spleen (the red pulp) which has a unique network that filters the blood, but also identifies any RBCs flowing through that don't pass the quality control test of squeezing and pressing. This helps to identify any damaged cells, remove them from circulation, and recycle the building block nutrients.

2. Extra Blood Reserve

In cases where the body experiences issues with adequate blood supply, such as shock, injury and/or significant loss of blood, the spleen can shrink in size and release up to 100 milliliters of blood into the circulation system. This represents 2% of the body's entire blood supply and is a backup system to maximize the opportunity for life. 

3. Filtering Blood to Remove Invading Germs and Viruses

Pathogens are usually neutralized or destroyed in the lymph nodes. But if any manage to evade that process, they will continue to circulate in the lymph fluid and eventually get recirculated in the blood. At that point, the spleen will serve as a backup filtration system. Bacteria, parasites, and debris are eliminated to ensure the blood stays clean. This is primarily done in the white pulp where macrophages engulf and degrade dead cells, tumor cells, and foreign material. During a chronic infection, the spleen may become inflamed from the accumulation of pathogens and increase in size. In addition, B cells (a type of white blood cell) will produce infection-fighting antibodies which can attack bacteria and viruses. This antibody production of B cells is one of the most important contributions the spleen makes toward immunity. 

Spleen Rupture and Stroke

Medical science reports that the spleen is the most vascularized organ in the body. This means that it has the most capillary vessels carrying blood or lymphatic fluid than any other organ. It is a sponge. Any serious injury or bleeding involving the spleen will result in significant blood loss and possible death. This is why the spleen is often removed following blunt abdominal trauma. In addition, similar to the brain or the heart, the spleen can also have a 'stroke' where an artery or capillary gets blocked by a blood clot. COVID-19 and especially the COVID-19 mRNA vaccine caused blood clotting in small blood vessels. Cases of spontaneous spleen rupture have been reported in several countries including the United States. The symptoms of brain stroke and heart attacks are widely known, but spleen stroke is not. It usually causes abdominal pain on the left side of the body and may include nausea and vomiting. Being aware of this is the first step and surgical removal of the spleen is the last. Unfortunately, removing the spleen can lead to severe infection and mortality risk, but it is the lesser of two evils at that point. Prevention of spleen stroke by supporting your immune system is the best course of action to reduce your health risk and vulnerability.

​See my book to learn more about the role of nutritional glycobiology in helping our spleen and immune system function optimally.