Diseases of the spleen and bleeding
Last reviewed: 23.04.2024
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In structure and function, the spleen resembles two different organs. White pulp, consisting of periarterial lymphatic membrane and germinal centers, functions as an immune organ. Red pulp, consisting of macrophages and granulocytes lining the vascular space (chords and sinusoids), functions as a phagocytic organ.
White pulp is the place of production and maturation of B- and T-cells. B cells in the spleen generate protective humoral antibodies; in certain autoimmune diseases [eg, immune thrombocytopenic purpura (ITP), Coombs-positive immune hemolytic anemia], autoantibodies can be synthesized to circulating blood elements.
Red pulp removes antibody-coated bacteria, old or abnormal red blood cells and antibody-coated blood cells (which can occur in immune cytopenias, such as ITP, Coombs-positive hemolytic anemia, and certain neutropenia). Red pulp also serves as a reservoir for blood elements, especially leukocytes and platelets. During the passage of red blood cells, the spleen removes the included corpuscles, such as Heinz body (precipitated insoluble globulin), Howell-Jolley body (fragments of nuclei) and whole nuclei; Thus, after splenectomy or functional hyposplenic status, red cells with these inclusions appear in the peripheral circulation. Hemopoiesis usually occurs in the red pulp only during the intrauterine period. After the prenatal period, hemopoiesis in the spleen can occur with bone marrow damage (eg, fibrosis or tumor), causing the hematopoietic stem cells to exit into the circulation and colonization of the adult spleen.
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