The present invention relates to antibodies and related molecules that specifically bind to CK-B4. Such antibodies have uses, for example, in the prevention and treatment of cancer as well as immune system diseases and disorders including cancers, as well as immune system diseases and disorders including autoimmune diseases, inflammatory disorders, immunodeficiencies, infections, HIV, arthritis, allergy, psoriasis, dermatitis, and inflammatory bowel disease. The invention also relates to nucleic acid molecules encoding anti-CK-B4 antibodies, vectors and host cells containing these nucleic acids, and methods for producing the same. The present invention relates to methods and compositions for preventing, detecting, diagnosing, treating or ameliorating a disease or disorder, especially cancers, as well as immune system diseases and disorders including autoimmune disease, inflammatory disorders, immunodeficiencies, infections, HIV, arthritis, allergy, psoriasis, dermatitis, and inflammatory bowel disease, comprising administering to an animal, preferably a human, an effective amount of one or more antibodies or fragments or variants thereof, or related molecules, that specifically bind to CK-B4.