Antibodies having dual specificity for two different but structurally relatedantigens are provided. The antibodies can be, for example, entirely humanantibodies, recombinant antibodies, or monoclonal antibodies. Preferredantibodies have dual specificity for IL-1.alpha. and IL-1.beta. and neutralizeIL-1.alpha. and IL-1.beta. activity in vitroand in vivo. An antibody of theinvention can be a full-length antibody or an antigen-binding portion thereof.Methods of making and methods of using the antibodies of the invention arealso provided. The antibodies, or antibody portions, of the invention areuseful 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.
