Allogeneic bone marrow transplantation

Allogeneic bone marrow transplantation involves the transfer of marrow from a donor to another person. The donor and recipient may be:

• monozygotic twins - known as syngeneic transplantation
• HLA matched siblings
• unrelated, but closely HLA matched
• related, but less than perfectly HLA matched

The oldest age for allogeneic transplantation is usually considered to be 40 to 55 years. Increasing age is associated with poorer results due to a higher frequency of graft versus host disease. T cells may be removed from the graft to ameliorate the manifestations of GVHD.

Donation involves the aspiration of about 1L of bone marrow. The recipient is given high dose ablative chemotherapy and, in all but those with aplastic anaemia, total body irradiation. The goals are to:

• provide sufficient immunosuppression to avoid destruction of the allograft by residual, immunologically active, host cells
• destroy residual cancer cells
• provide space for the new marrow to grow

The donor marrow cells are infused intravenously and localise in the marrow. The peripheral blood count rises within 2-4 weeks.

The results of allogeneic transplant undertaken in first complete remission are much better than those in relapse.