The most recent study, involving 29 people with CFS, shows that repeated rituximab infusions can keep symptoms at bay for years (PLoS One, DOI: 10.1371/journal.pone.0129898). "Eleven of the 18 responders were still in remission three years after beginning the treatment, and some have now had no symptoms for five years," says Fluge. "Suddenly, their limbs started to work again and their hands were no longer cold or sweaty."
The researchers think antibodies are to blame in at least a proportion of people with CFS. Relief started four to six months after the first dose of rituximab, approximately the time it would take for existing antibodies to be cleared from the body. Participants relapsed after about a year – roughly how long B-cells take to regrow and start making new antibodies. "We think the pattern of responses and relapses involves some mechanism with these antibodies," says Fluge.