From the Guidelines
The spleen plays a crucial role in the human body, serving as a blood filter, immune system component, and site for lymphocyte production and maturation, with its functions including removing old red blood cells, storing platelets, and producing antibodies. The spleen's immune functions are vital for fighting infections, and its absence can lead to increased susceptibility to certain infections, such as those caused by encapsulated bacteria like Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis 1.
As part of its immune function, the spleen contains white blood cells that help identify and destroy pathogens. It also stores a small reserve of blood that can be released during emergencies like hemorrhage. Additionally, the spleen produces antibodies and serves as a site for lymphocyte production and maturation, particularly B cells that are crucial for immune responses 1.
Some key functions of the spleen include:
- Filtering the blood to remove old and damaged red blood cells
- Storing platelets and a small reserve of blood
- Producing antibodies and serving as a site for lymphocyte production and maturation
- Acting as a component of the immune system to fight infections
- Serving as a hematopoietic organ during fetal development, producing blood cells before the bone marrow takes over this role 1.
In the absence of a spleen, individuals are at increased risk of developing overwhelming post-splenectomy infection (OPSI), which can be life-threatening 1. To mitigate this risk, asplenic individuals may require prophylactic antibiotics and specific vaccinations, such as those against Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis 1. Annual influenza vaccination is also recommended for asplenic individuals over 6 months of age to reduce the risk of secondary bacterial infections 1.
From the Research
Functions of the Spleen
The spleen is a vital organ that performs several important functions in the body. Some of the key functions of the spleen include:
- Filtering the blood of pathogens and abnormal cells 2, 3
- Regulating the immune response to blood-borne antigens 2, 4
- Removing old or damaged red blood cells from the blood 3, 5
- Producing antibodies to fight infections 6
- Acting as a center for the blood defense system, working together with the liver and bone marrow to eliminate blood-borne pathogens 6
Immune Functions
The spleen plays a crucial role in the immune system, with its white pulp and red pulp working together to initiate immune reactions to blood-borne antigens 3. The spleen is also responsible for:
- Filtering the blood of foreign material and old or damaged red blood cells 3
- Regulating the T and B cell response to antigenic targets in the blood 2
- Producing specific antibodies to fight infections, including IgM and IgG2 antibodies 6
Red Blood Cell Clearance
The spleen is also responsible for clearing senescent and altered red blood cells from the blood 5. This process involves:
- Prefiltration, filtration, and postfiltration of red blood cells in the red pulp of the spleen 5
- Phagocytosis of retained red blood cells by macrophages in the spleen 5
- Biomechanical processes driving the postfiltration phagocytosis of red blood cells, including cell deformation and adhesive strength 5