Selective blockade of CD28 signalling, either with anti-CD80/CD86 or cytotoxic lymphocyte-associated antigen-4 (CTLA4)-Ig (soluble protein binding to CD80/86), has been applied clinically in the treatment of autoimmune diseases, such as rheumatoid arthritis, and in melanoma [130,131]. Here, CD80 is linked to autoimmune disease.