Question 3#

All of the following are functions of the spleen EXCEPT:

A. Clearance of damaged or aged red blood cells (RBCs) from the blood
B. Extramedullary site for hematopoiesis and recycling iron
C. Initiation of adaptive immune response from filtration of lymph
D. Clearance of encapsulated bacteria from the bloodstream

Correct Answer is C


The spleen has both fast and slow circulation of blood. It is during slow circulation that blood travels through the reticular spaces and splenic cords where it is exposed to contact with splenic macrophages which remove senescent blood cells. Through this process the spleen is also able to remove erythrocyte inclusions such as Heinz bodies without lysing the cells. Through the reticuloendothelial system the spleen clears encapsulated bacteria such as pneumococcus and Haemophilus influenzae which are poorly opsonized from the hepatic reticuloendothelial system. In addition to these functions the spleen serves as an extramedullary site for hematopoiesis and plays a functional role in the recycling of iron. While the white pulp of the spleen is important in the initiation of the adaptive immune response, material is delivered to the spleen through the blood and not the lymph.