Antibodies having dual specificity for two different but structurally related antigens are provided. The antibodies can be, for example, entirely human antibodies, recombinant antibodies, or monoclonal antibodies. Preferred antibodies have dual specificity for IL-1 alpha and IL-1 beta and neutralize IL-1 alpha and IL-1 beta activity in vitro and in vivo. An antibody of the invention can be a full-length antibody or an antigen-binding portion thereof. Methods of making and methods of using the antibodies of the invention are also provided. The antibodies, or antibody portions, of the invention are useful for detecting two different but structurally related antigens (e.g., IL-1 alpha and IL-1 beta) and for inhibiting the activity of the antigens, e.g., in a human subject suffering from a disorder in which IL-1 alpha and/or IL-1 beta activity is detrimental.
