Expansion
Filtration, immunity, storage and, in the fetus, haematopoiesis
Expansion
Functions
- Filtration: removal of aged and abnormal red cells, and of opsonised bacteria
- Immunity: a major site of antibody production, especially IgM; contains about a quarter of the body’s lymphoid tissue and produces properdin and tuftsin
- Storage: platelets (about a third of the total), and in some species red cells
- Haematopoiesis in the fetus, and again in myelofibrosis
After splenectomy or in hyposplenism
- Risk of overwhelming post-splenectomy infection with encapsulated organisms: pneumococcus, meningococcus, Haemophilus influenzae type b, and also Capnocytophaga from dog bites and severe malaria and babesiosis
- Blood film: Howell-Jolly bodies, target cells, Pappenheimer bodies, thrombocytosis and lymphocytosis
Prevention: vaccination against pneumococcus, meningococcus and Hib, ideally 2 weeks before elective splenectomy, annual influenza vaccine, lifelong prophylactic penicillin, a medical alert card, and early treatment of febrile illness.
Causes of functional hyposplenism include sickle cell disease, coeliac disease and inflammatory bowel disease.