CTLA4 and colitis: For instance, mice deficient in CTLA-4 (CTLA-4-/-) or treated with CTLA-4 inhibitors developed inflammatory and autoimmune diseases characterized by substantial lymphocyte infiltration and tissue damage including diabetes, multiple sclerosis, rheumatoid arthritis, myasthenia gravis, pancreatitis, thyroiditis, systemic lupus erythematosus, and colitis (81).