What is Graft vs. Host disease?

Hi, Dr. Langston. What exactly is graft versus host disease? [MUSIC PLAYING]

So when we do an allogeneic transplant for a patient with a blood disorder, what we're doing

is we're giving them a graft from a donor. And it consists of the seed cells that

repopulate the bone marrow. But it also consists of immune cells that will reconstitute the patient's immune system.

And it's this immune cell transfer that really is at the root of graft versus host disease, because these immune cells are infused into the patient.

They find themselves in a new environment. They recognize they're not in the right place. And they begin to react against the recipient or the host.

And this is what we call graft versus host disease. Graft versus host disease is less likely to occur when the donor and the recipient

are very closely matched. When we talk about compatibility for a transplant, we're looking at a series of genes

called HLA, which are located on human chromosome six. These are the antigens that form the basis of what

we call the transplant barrier. So in order for a transplant to be successful, there needs to be relatively close

matching between the donor and the recipient at these particular genes. So testing for those genes is really

critical in terms of selecting donors for transplantation. If we think about how a transplant works,

we actually want a little bit of this graft versus host reaction because it actually fights against the cancer.

And that's actually why transplantation can cure patients that cannot be cured by chemotherapy alone.

What we don't want is we don't want severe graft versus host disease, because severe graft versus host disease

can be life-threatening. About half of patients will develop at least some symptoms or signs of graft versus host disease.

Fortunately, with modern immune suppressive approaches, the majority of those people will have mild graft versus host disease that's easily managed.