Its fundamental role in immune homeostasis is further supported by several early experimental studies, which have shown that CTLA-4-deficient mice suffer generalised lymphocyte activation and multiorgan infiltration with lymphocytes, dying from fatal autoimmune disease within weeks from birth [31,32], whereas deletion of CTLA-4 in adult mice resulted in a condition similar to Sjögren’s syndrome [33], thus suggesting more complex underlying mechanisms. This evidence concerns the gene CTLA4 and autoimmune disease.