Why is graft-versus-host disease sometimes a good thing to have?
Graft-versus-host disease is sometimes a good thing to have because as well as the immune system from the new bone marrow “rejecting the body” it also rejects the cancer cells. This is called the graft-versus-leukemia or GVL effect. There are a number of lines of evidence that support this concept. If you perform a bone marrow transplant using an identical twin as the donor, patients don’t develop GVHD. However, the relapse rate after bone marrow transplant is much higher than when you use marrow from a brother or sister who is the same tissue type but not identical. It has also been shown that there is also a lower rate of relapse in people who develop GVHD. The strongest evidence is when someone relapses after an allogeneic transplant they can go into remission if you give back white cells from the original donor.
