The invention relates to an isolated immunoglobulin heavy chain polypeptide and an isolated immunoglobulin light chain polypeptide that bind to interleukin-33 (IL-33). The invention provides an IL-33-binding agent that comprises the aforementioned immunoglobulin heavy chain polypeptide and immunoglobulin light chain polypeptide. The invention also provides related vectors, compositions, and methods of using the IL-33-binding agent to treat a disorder in a mammal that is responsive to IL-33 inhibition.