By James Gallagher Health reporter, BBC News:
Dr Charles Shepherd, the UK ME Association's medical adviser, said: "The results of this clinical trial are very encouraging news for people with ME.
"Firstly, they help to confirm that there is a significant abnormality in immune system function in this disease.
"Secondly, they indicate that altering the immune system response in ME could be an effective form of treatment for at least a subset of patients.
"We now need further clinical trials of such anti-cancer agents to see if other research groups can replicate these findings."