The primary function of the spleen is filtration of blood and immune response. It helps remove old or damaged red blood cells from circulation, recycling iron and other components. The spleen also plays a role in the body’s immune system; it detects and responds to pathogens, producing lymphocytes that assist in fighting infections. Additionally, the spleen stores platelets and white blood cells, releasing them as needed during injury or infection. Although not essential for survival, the spleen contributes to overall health by helping manage blood quality and immune function.