The red pulp of the spleen is where the filtration and removal of old or damaged red blood cells and foreign particles from the blood occur. This process is known as phagocytosis and is performed by macrophages located in the red pulp. The red pulp also serves as a site for the storage of platelets and the production of new red blood cells in some animals. The white pulp of the spleen, on the other hand, is involved in immune functions, such as the production of antibodies and the activation of T-cells in response to infections or other foreign substances.