Methods of inhibiting or reducing the incidence or the severity of immunotherapy-related toxicity in a subject, the method comprising a step of administering a recombinant hGMCSF antagonist to the subject, wherein said administering inhibits or reduces the incidence or the severity of immunotherapy-related toxicity in said subject, are provided. An hGMCSF antagonist for use in methods of inhibiting or reducing the incidence or the severity of immunotherapy-related toxicity in a subject also are provided.