The invention relates to an isolated immunoglobulin heavy chain polypeptide and an isolated immunoglobulin light chain polypeptide that bind to a protein encoded by the T Cell Immunoglobulin and Mucin Protein-3 (TIM-3). The invention provides a TIM-3-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 TIM-3-binding agent to treat a disorder or disease that is responsive to TIM-3 inhibition, such as cancer, an infectious disease, or an autoimmune disease.