Rheumatoid arthritis is believed to occur when the immune system attacks the tissue lining the joints, so researchers have been investigating whether dampening down the immune system could be an effective treatment of last resort.

Dr. Sarah Bingham, of Leeds General Infirmary in Britain, said results of a small pilot study in Leeds showed that 60% of those treated improved, though she stressed the treatment was not a cure.

"It is like giving a short, sharp shock to the immune system to dampen it down," she said in an interview after presenting her findings to the European League against Rheumatism congress in Stockholm.

"The results so far are encouraging. Patients notice an improvement the next day. One of my patients had absolutely no disease activity at all. She has since relapsed quite badly but she says that just for those 9 months it was worth it."

Bingham estimated up to 10% of rheumatoid arthritis patients fail to respond to drug therapies. Those offered the new treatment were patients who had "really badly swollen joints and a terrible quality of life."

The treatment involves the use of cyclophosphamide chemotherapy to damage but not completely destroy the immune system. The immune system is then "rescued" by transplanting back some of the patient's own stem cells.

Bingham said a total of 73 patients with severe rheumatoid arthritis that did not respond to conventional treatment were known to have undergone the novel therapy at different centres around the world. Results showed 67% achieved at least a 50% improvement at some point after their transplant.

Most patients were re-started on conventional drug therapies within 6 months for persistent or recurrent disease activity. However, disease control was achieved in about half the cases whereas conventional medication had previously been ineffective.

She concluded that the new procedure was a "relatively safe form of salvage treatment." Although not a cure, the hope was that if the disease came back it could be kept under control by drugs.

The meeting heard that the European League against Rheumatism and the European Group for Blood and Marrow Transplantation are now starting a trial to compare the safety and efficacy of smaller doses of cyclophosphamide with transplant against cyclophosphamide and conventional drugs.