Here you will find definitions and meanings of some of the most frequently used terms on the site.
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This is the immune attack by lymphocytes in a donor’s marrow or blood cell suspension (the graft) against the tissues of the recipient (the host). The immune cells most engaged in this reaction are donor T lymphocytes, which are present in the donor’s blood or marrow, the source of the stem cells. The principal sites of injury are the skin, the liver and the gastrointestinal tract. The reaction does not occur in identical twin transplants. The reaction may be minimal in closely matched individuals or severe in less well-matched individuals. These reactions are mediated in part by antigens that are not in the major HLAsystem and cannot be matched prior to transplantation. For example, in the case of a female stem cell donor and a male recipient, factors that are produced by genes on the male recipient’s Y chromosome may be seen as foreign by the female donor’s cells, which do not share the genes on the Y chromosome. This fact does not prohibit female donors and male recipients, but it makes the risk of immune reaction higher.
This is the potential immune reaction of transplanted (donor) T lymphocytes to recognize and attack the malignant cells of the recipient. This effect was noted when 1) disease recurrence after transplant was seen to be more likely if the donor and recipient were identical twins than if they were non-identical siblings; 2) disease recurrence was less likely the more pronounced the graft-versus-host disease (GVHD) was; and 3) the removal of donor T lymphocytes decreased the incidence of GVHD but also resulted in a higher frequency of disease relapse. Each of these observations could be explained best as an immune attack by donor lymphocytes against recipient tumour cells that, along with the intensive conditioning treatment, serves to keep the disease in check. This effect seems to be most active in types of myeloid leukaemia, although it may also occur in patients with other blood cancers.
A type of white cell that has a large number of granules in the cell body. Neutrophils, eosinophils and basophils are types of granulocytes.
A chemical used to stimulate the production of neutrophils and shorten the period of low neutrophil counts in the blood after chemotherapy. Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are examples of growth factors that are made commercially. GM-CSF can also stimulate monocytes.