A treatment for the debilitating condition rheumatoid arthritis has been shown to improve symptoms by up to 70%, and may help explain its cause.

UK researchers who tested the effect of a drug called Rituximab found it appeared to interrupt the process that causes inflammation of the joints in the condition.

The study also gave a picture of exactly how rheumatoid arthritis works, confirming existing scientific theories.

The team from University College London say their discovery means a cure for the condition is "firmly on the agenda", though arthritis campaigners are more cautious about the findings.

We're talking about remission here rather than a 'cure'

Arthritis Research campaign spokeswoman

Around 387,000 people in the UK suffer from rheumatoid arthritis, the form most associated with severe physical handicap.

It is three times more common amongst women than men, and a recent study showed women with the condition were 60% more likely to die early than healthy women.

'Brilliant response'

The UCL team is presenting results from their ongoing research into Rituximab at the American College of Rheumatology Congress in New Orleans.

The 122 patients studied were given two doses of Rituximab plus another drug called methotrexate.

Half of the 122 patients studied showed "major improvements" with a 50% reduction in symptoms, and a further 23% showed a "brilliant response", seeing a 70% reduction in symptoms, the researchers said.

The drug acts by suppressing antibody production within the immune system, breaking a key part of the cycle that causes inflammation.

It does that by limiting the amount of immune cells called B-cells. These interact with other immune cells and become activated.

They can also develop into plasma cells which produce antibodies to defend the body, such as "rheumatoid factors", where the body attacks healthy cells, which could contribute to rheumatoid arthritis.

Rituximab removes B-cells from the blood, helping to eliminate the problem at the source.

'Re-booting the immune system'

Professor Jo Edwards, who led the study, said: "An arthritis cure is now firmly on the agenda. This study proves the scientific validity of the benefits of Rituximab to rheumatoid arthritis sufferers.

He added: "It's like having a bug in your computer; Rituximab re-boots part of your immune system and when you switch it back on the bug is gone."

He said the drug appeared to be as good as the best drugs currently available, but that its benefits lasted much longer, on average up to a year.

"Patients given Rituximab in the study have been able to return to work and in some cases have taken up more strenuous activities such as sports, going to the gym and joining walking clubs," he said.

A spokeswoman for the Arthritis Research Campaign said the results were "extremely positive" and "very, very encouraging".

But she said the improvement in symptoms was little better than in patients taking other new therapies and it was unclear how long the remission lasts.

She added: "We're talking about remission here rather than a 'cure'.

"As a future treatment for severe rheumatoid arthritis, Rituximab looks promising. The results of larger trials over a longer period of time will undoubtedly answer some of our concerns."