[curlygirl]

The thymus is implicated a lot in aplastic anemia/pancytopenia. If you google thymus and pancytopenia you'll see in rare cases people with cancer of the thymus had their thymus removed and their pancytopenia improved spontaneously. ATG stands for anti-thymocyte globulin, and while ATG is given to kill off the T-cells, it actually kills of the thymocytes that form the T-cells. Here is what thymocytes are (from wikipedia):

"Thymocytes are hematopoietic progenitor cells present in the thymus.[1] Thymopoiesis is the process in the thymus by which thymocytes differentiate into mature T lymphocytes. The primary function of thymocytes is the generation of T lymphocytes (T cells). The thymus provides an inductive environment, which allows for the development and selection of physiologically useful T cells. The processes of beta-selection, positive selection, and negative selection shape the population thymocytes into a peripheral pool of T cells that are able to respond to foreign pathogens and are immunologically tolerant towards self antigens."

So thymocytes are implicated in our defective T-cell response: in AA there are too many killer T cells and not enough regulatory ones. Our doctor explained it to me because I was confused about my son's bone marrow biopsy results: He always had normal levels of lymphocytes in his marrow (in the 30%s) but in the blood it would be in the 70-80%. So it wasn't the marrow that was the problem, it is the T cells that are developing in his thymus (in theory). But somehow the immune system from the bone marrow is involved, too, because the bone marrow transplants work.

I think it's great that they're looking into this for you. You'd think they could just take anyone's thymus out but they can't. It's integral to growth in children. But it starts shrinking rapidly after puberty.