The present invention concerns immunoglobulins, such as antibodies, which specifically bind Oncostatin M (OSM), particularly human OSM (hOSM) and modulate the interaction between OSM and gp130. In typical embodiments, OSM is glycosylated. The invention also concerns antibodies that modulate the interaction between both Site II and Site III of OSM and their respective interacting partners. Further disclosed are pharmaceutical compositions, screening and medical treatment methods.