Spleen Function in Immune System

Spleen is a Silent Worker that serves several invaluable roles in our body – And it is today thought to be pivotal in regulating the immune system, involved in endocrine function with regard to non-alcoholic fatty liver disease and a metabolic asset.

You may have heard people using the phrase “venting spleen” – not referring to the organ itself, but as a method to describe letting out frustration or anger. The term “spleen” has been used metaphorically as a synonym for “anger” – because in the medieval era, spleen was believed to be the literal, physical factory of hot temper. People of the medieval times assumed that venting their spleens would likely climate excess anger. Fortunately,  since then we have learnt a lot more about spleen function in human body.

The Spleen!!

While most people heard of a spleen, but only a few can tell you anything about it. Spleen is considered a neglected body organ. It has always been thought of as an ancillary organ in portal hypertension or organ localization in lymphoproliferative disorders, even thought it had substantial attention in infectious ailments for some time. That is such a pity, as spleen is an important organ that clearly exhibits the handiwork and wisdom of our creator. Although spleen serves highly important functions in our body, when necessary we can survive without it – thanks to the very accommodating liver.

Since 1952, when King Schumacker reported distressing post- splenectomy infection, there has been a rising recognition of significance of the spleen in human body. In addition, doctors often come across the complaints of spleen enlargement. In the past few years, following the rigorous research and in-depth studies of spleen structure, secretions, cell function, organizations and interventions, a better understanding of numerous functions of spleen has been gained. It is accepted that spleen filters the blood and is an eminent regulation center of the body’s metabolic, immune and endocrine system as well.  Read on to know the functions of spleen in detail.

Spleen Functions– The blood-filled organ performs several vital functions!!

The spleen blends the adaptive and innate immune system in an inimitably organized manner. The structure of spleen facilitates it to eliminate older erythrocytes from the blood circulation and helps in efficient amputation of cellular debris and blood-borne micro-organisms. This function, in conjunction with an organized lymphoid compartment, makes spleen an important organ for antifungal and antibacterial immune reactivity.

A blood filter

One of the most important functions of spleen is to filter harmful particles and micro-organisms that have entered our bloodstream. For example, in various studies, scientists have observed that foreign dye particles discoloring the blood can be fully removed in one pass via the spleen.

Not just does the spleen wipe out foreign micro-organisms and particles, it eliminates defective and damaged red blood-cells. And because of this, the spleen may have to be surgically removed from patients suffering from sickle cell anemia lest the spleen obliterate all of the defective sickle-shaped red blood cells. After all even bad blood is better than to have no blood in the body.

The removal of malformed blood cells happens in certain places of the spleen, known as red pulp, named so as this area is a hub of red blood cells. Red blood cells typically circulate in our blood vessels for 120-days before they wear out. During its life span of 120-days, each red blood cell makes several trips through the spleen, wherein it is subjected to undergo a taxing gauntlet that examines cell flexibility, health and function. The red blood cells failing to pass the tests are washed off from the circulation.

Blood passing via the spleen may take either a direct closed way via its blood cells or an indirect open way, where the blood leaves the blood vessels temporarily.  In case, the blood leaves the blood vessels almost anywhere in the body, it results in substantial internal bleeding or blood clotting. The cells that temporarily leave the blood vessels in the red pulp must find their way back into the circulation via squeezing through the walls of special blood vessels known as sinusoids. This strange arrangement actually assesses the flexibility of the red blood cells.

The spleen’s sinusoids walls are made of attenuated cells, which appears like wood staves forming the wooden barrel wall. Special reticular fibers hold together the stave- like cells – same like the metal strapping around the wooden barrel. Blood cells get back into the blood circulation by squeezing between the sinusoid’s stave-like cells.

The intimately packed cells act like a clothes wringer. When the blood cells passes via the sinusoid wall, it is squeezed so tightly that both sides of the cell membranes touch one-another. In case, the red blood cells feature any abnormal granules or inflexibility, it is eliminated from the circulation and demolished by nearby cells called ‘macrophages’ – the big eaters. The iron in the cells’ hemoglobin is then recycled to make new red blood cells.

Blood and Platelets Reservoir

Another important spleen function is storage of blood and platelets. Although the spleen is just about the size of our fist, at any given time around 4% of all blood in our body is passing via the spleen.

In some carnivorous animals, spleen stores red blood cells packed together just like “paste”, which can render a “blood transfusion” in the event of grave wound. The human spleen however, fundamentally stores blood cells – around 1/3rd of body’s platelets. Platelets are special cell residues circulating in the blood. They avert excessive external or internal bleeding by means of forming clots that plug destroyed blood vessels same like a self-sealing tire.

Lymphoid Function of Spleen

When a spleen is sliced open, it features an overall red appearance because of its dense concentration of red blood cells. However, scattered throughout the red pulp are white patches called white pulp, which contain the colorless cells of our lymphoid system.

The lymphoid cells comprises of plasma cells and lymphocytes, which safeguard our body from infections by foreign cells, antigens and microorganisms. These cells are formed in our primary lymphoid organs (the thymus gland and bone marrow), and they find their way into secondary lymphoid organs ( tonsils, lymph nodes and the spleen) where they perform their protective function as part of immune system.

The spleen’s white pulp is rich in “T and B lymphocytes” from the thymus gland and bone marrow respectively. When antigens are found in the blood, B lymphocytes turn into plasma cells, which create and release antibodies into the blood to raze the antigens.

Early in our development in the mother’s womb, T cells learn to identify the proteins for our body and distinguish them from antigens. Throughout our lives, T cells continuously scan the cells surface looking for protein residual and foreign proteins that indicate a cell is infected with virus or has turned cancerous. When an antigen is detected, the cell having it is abolished by the T cell in a procedure called “cell-mediated immunity.”

This function of T cells describes graft rejection by people who have organ or tissue transplants. T cells may be harmfully affected by diseases that impair the immune system like cancers (lymphoma) or AIDS.

Always economical, spleen saves useful elements from the old cells like iron. It stores iron in the form of bilirubin or ferritin, and eventually it returns the iron to the bone marrow, where hemoglobin is manufactured.

Diseases that Disrupt Spleen Functions

Just like any other body part, spleen can be damaged by some disease or trauma. To finish off, we will take a glance at the prominent causes of malfunction of spleen:

  • Enlarged Spleen / Splenomegaly:

An enlarged spleen is typically caused by blood cancers, viral mononucleosis, liver disorders or some other conditions. Moreover, trauma to the spleen can also cause it to enlarge.

  • Sickle Cell Disease:

In this inherited type of anemia, abnormal or defective red blood cells hinder the flow of blood via vessels and can lead to organ damage including spleen damage. People suffering from sickle cell anemia need immunizations to avert illnesses that spleen helps to fight.

  • Ruptured Spleen:

The spleen is susceptible to injury, and a ruptured spleen can cause life-threatening internal bleeding and medical emergency. An injured spleen may rupture immediately after an accident and in some instances, days/weeks after an accident

  • Thrombocytopenia (or Low Platelet Count):

An enlarged spleen sometimes stores excessive amount of platelets, which results in abnormally few platelets circulating in bloodstream.

Can I live without My Spleen?

Yes, Spleen is useful, but it is not a vital organ.

Sometimes, the spleen is removed surgically from the human body, and this may be done in cases when spleen becomes injured and it is adversely affecting the body or has be removed in course of transplantingother organs. Other organs of the body, including your liver or lymph nodes are able to sweep in and take over the many spleen functions. Since spleen is an extremely useful organ, people without spleens are more open to infections. The doctor may advise you to take additional precautions like getting vaccinations and prescribe you oral medications, once your spleen has been removed.

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