PLoS ONE: Benefit from B-Lymphocyte Depletion Using the Anti-CD20 Antibody Rituximab in Chronic Fatigue Syndrome. A Double-Blind and Placebo-Controlled Study

Rituximab targets and destroy B cells. The B cells are eliminated within weeks , but autoantibodies typically survive in the body for another two or three months. "Washing out these antibodies is the most probable explanation for the time lag in benefits," acccording to the authors.
UK ME Association.
Chronic fatigue genes and risk factors