Irish team to lead research on leukaemia "suicide cells"

AN Irish group has been chosen to head a European research effort to improve the treatment of leukaemia by causing specific cells to commit "suicide".

The EU funded work will be coordinated by Dr Mark Lawler and Prof Shaun McCann of the Department of Haematology and Oncology at St James's Hospital, Dublin, and Trinity College. The project also involves research groups in the Netherlands Germany, France, Italy and the UK.

Leukaemia is a form of cancer that affects the blood, and two to three cases per 100,000 occur in Ireland each year. St James's specialises in leukaemia treatment using bone marrow transplants at its National Bone Marrow Transplant Unit.

Rejection of transplanted tissue is a common problem with organ donations, but the situation is reversed with marrow, Dr Lawler explained. There is a greater danger that the transplanted marrow will attempt to reject the recipient which leads to a condition known as graft versus host disease.

The disease is caused when the marrow produces T cells which launch an immune attack on the host. The reaction can cause death in some cases.

Yet doctors have bound that if the T-cells are not present, the marrow transplant will fail.

The research is an attempt to reconcile the need to have T-cells present and the risk that they may cause damage. "We want the happy medium where we get the good effects of the T-cells without getting the disease," Dr Lawler said.

The answer is to alter the T-cells so that they will commit suicide on command if they begin to attack the host. Dr Lawler and the international team are attempting to achieve this using a technique known as suicide gene therapy.

It is a complex procedure which begins with the collection of Tcells from the donor's blood. A "foreign" gene is spliced into the T-cell's own genetic blueprint. The cells and the marrow can then be transplanted into the patient.

The gene has no effect on the T cell's normal functions and here things rest unless graft versus host disease develops.

In this case a special non toxic drug is given that can react only with substances produced by the suicide gene. Together these, chemicals cause the T-cell to self destruct, halting the graft versus host disease reaction.

A great advantage is that this, work can be carried out in the lab oratory without risk to a patient.