IL-18 is highly expressed in chronic phases of skin diseases such as eczema, lupus erythematosus and psoriasis but also in e.g. lupus nephritis, chronic joint diseases and graft-versus-host disease [17], [24], [25], [26], [51], [52], [53], [54], [55], [56], [57]. This evidence concerns the gene IL18 and graft versus host disease.