Antibody Treatment for Advanced Celiac Disease

Background: \- Celiac disease is a condition where the immune system attacks the cells of the small intestine. The intestine becomes inflamed and cannot digest food properly. The disease most often causes a reaction to foods that contain gluten. Most people can treat celiac disease with a gluten-free diet. However, some people have digestion problems even on a gluten-free diet. Researchers want to try a new antibody therapy for celiac disease. The treatment may block the immune reaction that causes the disease. They will test this antibody in people who have celiac disease that has not responded to a gluten-free diet. Objectives: \- To see if antibody therapy is a safe and effective treatment for celiac disease that has not responded to standard treatments. Eligibility: \- Individuals at least 18 years of age who have been on a gluten-free diet for 6 to 12 months but still have symptoms of celiac disease. Design: * Participants will be screened with a physical exam and medical history. Blood samples will be collected. These samples will help determine if the specific antibody treatment is likely to work. * Before the start of the study, participants will have a biopsy of the small intestine. * Participants will receive three doses of the study antibody as injections. These doses will be given 3 weeks apart. * Treatment will be monitored with blood tests and heart function tests. Participants will also have a second small intestine biopsy within a week after the last dose of the antibody.