I have never heard of, and can find no evidence of, transplanting a spleen. He is very conscientious in doing what he can to avoid exposure at this dangerous time, but I am wondering what he and others with his condition can do to further protect themselves. — B.S.

ANSWER: The spleen is an organ that removes damaged blood cells, but it is also an important part of the immune system, and acts as a kind of super lymph node — a place where white blood cells congregate and become activated. People without spleens are primarily at risk due to the immune system effects, as the liver takes over the job of removing worn-out blood cells.

Spleen transplants have been tried, but are not likely to be successful as a single organ transplant. However, in people who are undergoing a multiple visceral organ transplant (stomach, intestine, pancreas, with or without