Effect of anti-GM-CSF treatment prior to the onset of arthritis. (a) Severity (mean clinical scores ? SEM). (b) Cumulative incidence. Mice were treated intraperitoneally every second day from days 21 to 31 with anti-GM-CSF mAb or control mAb. *P = 0.05 and **P = 0.01 compared with control mAb-treated. GM-CSF, Granulocyte macrophage-colony stimulating factor; mAb, monoclonal antibody.