A CYTOTOXIC and an immunosuppressive drug (see IMMUNOSUPPRESSION). In the first of these capacities it is of value in the treatment of acute leukaemia. As an immunosuppressive agent it reduces the antibody response of the body (see ANTIBODIES), so helps facilitate the success of transplant operations (see TRANSPLANTATION) by reducing the chances of the transplanted organ (e.g. the kidney) being rejected by the recipient. It is also used in the treatment of AUTOIMMUNE DISORDERS.