Your Spleen and the Immune System
What Is the Spleen?
Located in the abdomen, the spleen is an organ involved in immune function. It is made up of lymphatic tissue marbled with a delicate network of veins and arteries.
What Does the Spleen Do?
The spleen has two primary functions: to filter the blood and to coordinate the immune response. The spleen is made up of two different tissues, the red and white pulps, each of which serves one of these functions.
The Red Pulp
The red pulp is the component of the spleen that handles filtration. It is characterized by a large number of blood-filled cavities and connective tissue. Blood comes to the spleen through the splenic artery. This artery divides into finer and finer branches, permeating the spleen. This ensures that all the blood in the body is filtered by the spleen and any foreign matter is eliminated. Old and dying red blood cells are also removed at this juncture.
The White Pulp
The white pulp is located in little clumps inside the red pulp. It is made up of lymphoid tissue. The purpose of the white pulp is to make and mature immune cells and blood cells. Also, antibodies are often made by lymphocytes in the white pulp. B cells, T cells, macrophages, natural killer cells, and dendritic cells, all play a part in the function of the white pulp. Circulating dendritic cells and macrophages bring foreign objects found in the blood to the T and B cells in the spleen for identification. Once the foreign matter has been identified, an appropriate immune response is launched. If necessary, the B cells begin producing large amounts of antibodies.
Diseases That Affect the Spleen
Because of its role in filtering blood, the spleen is exposed to every foreign element that enters the body. Needless to say, this makes it vulnerable to the effect of these invaders. Malaria, leishmaniasis, and mononucleosis are a few of the many infections that can cause the spleen to become enlarged.
Various conditions of the blood (e.g. sickle cell anemia) can also cause damage to the organ. Should the spleen become enlarged, there is a risk that it may burst. If this happens, it must be removed. Removal of the spleen is a fairly safe procedure, and most people adjust well to life without it. Most immune functions continue to perform at normal levels, although missing the spleen does seem to predispose you to developing certain septic infections.