Q. This may be a silly question but…On the topic of anemia and increased RBC destruction, the lecture notes state that the spleen removes unusual shaped RBCs, causing anemia. Is it possible for the person’s spleen to be removed if they have sickle cell anemia so that the unusual shaped RBC’s aren’t destroyed?
A. That’s a great question!
It’s true that one of the jobs of the spleen is to remove unusually-shaped red cells. In hereditary spherocytosis, for example, the spleen destroys the patient’s unusually-shaped spherocytes (the macrophages in the spleen gobble them up), leaving the patient with fewer red cells and making the patient anemic. In hereditary spherocytosis, removing the spleen helps alleviate symptoms. Removing the spleen removes the site of destruction, so the spherocytes stay in the circulation, and the patient doesn’t get anemic. You only do this for really severe disease, though, because once you remove the spleen, you have to be vaccinated for life against certain bacteria.
In sickle cell disease, it’s a different story. In this disease, the main problem is not that the spleen is destroying red cells and removing them from the circulation (as is the case in hereditary spherocytosis). The main problem is that the sickle-shaped red cells are plugging up vessels and causing tissue damage. Sickle cells are non-deformable; they can’t negotiate tiny capillaries or squeeze through tiny spaces. So they end up getting stuck and piling up in tiny vessels all over the body – hands, feet, lungs, heart, brain – anywhere there is a capillary bed, sickle cells can plug it up.
This same plugging happens in the spleen; the sickle cells plug up little vessels, causing tissue death (from lack of blood flow). The little dead areas of spleen heal over, leaving scars behind. Eventually, the whole spleen is just a little scarred-up nubbin of tissue. This is called autosplenectomy.
Removing the spleen in sickle cell disease wouldn’t do much good; the patient would still have circulating sickle cells, which would continue to travel around the body, getting stuck in vessels and damaging tissues. In fact, this is what happens after autosplenectomy: sickle cells continue to plug up vessels just as they did before the autosplenectomy.