Therapeutic neutralization of GM-CSF reverses collagenase-induced arthritis pain and disease. C57BL/6 mice were treated therapeutically (from day 20) with either anti-GM-CSF or isotype control monoclonal antibody. (A) Change in weight distribution (pain) over time. (B) Quantification of arthritis development (histology) at day 42. (C) Representative histologic pictures of knee joints (safranin O/fast green stain) (original magnification ×100), arrow indicates cartilage damage. Results are expressed as the mean ± standard error of the mean; n = 10 to 15 mice per group (from two independent experiments). *P <0.05, **P <0.01, ***P <0.001, control versus anti-GM-CSF; # P<0.0001, control and anti-GM-CSF versus t = 0 readings. C: cartilage; GM-CSF: granulocyte-macrophage colony-stimulating factor; LF: lateral femur; LT: lateral tibia; M: meniscus; MF: medial femur; MT: medial tibia.