The role of the spleen in resistance to infection

The spleen serves two major critical functions in protecting against bloodstream bacterial infections--it is a phagocytic filter that removes bacteria from the bloodstream and it is an antibody-producing organ. Although the liver appears to remove the majority of well-opsonized bacteria from the bloodstream, the spleen plays an important role through its ability to sequester bacteria that are not as well opsonized and, thus, is of critical importance in the nonimmune host. The spleen may also be critical in the production of opsonizing antibodies, which are important for the rapid and efficient removal of bacteria from the bloodstream.