DISORDERS OF SPLEEN
Spleen is an encapsulated mass of red pulp, i.e. tortuous capillaries (cords of Billroth) and fenestrated splenic sinuses, surrounded by white pulp (periarterial lymphatic sheaths containing T and B lymphocytes).
A marginal dendritic zone of antigen-presenting cells separates red pulp from white pulp. Spleen receives ~5-6% of cardiac output, of which ~90% passes through micropores between splenic cords to sinuses for filtration.Important functions of spleen include:
• Filtration, i.e. removal of senescent, deformed or antigen coated cells, i.e. culling, from circulation and their destruction
• Repair of damaged RBCs and other cells by removal of intracytoplasmic inclusion bodies and other cell debris from RBCs, i.e. pitting
• Reservoir for extra platelets and factor VIII, released on splenic capsular contraction by adrenaline, when required.
• Hematopoiesis in early fetal life (lt;3-6 months) or postnatal extramedullary erythropoiesis in severe hemolytic anemia.
• Immunological function, i.e. synthesis of IgM, properdin and Tuftsin-a phagocyte promoting tetrapeptide.
19.16.1