Overexpression of IL-15 has been shown to be involved in several autoimmune disorders including rheumatoid arthritis (RA) (20, 27), psoriasis (41), inflammatory bowel diseases (59), celiac disease (25, 60), lupus (21), vitiligo (61), alopecia areata (62), and multiple sclerosis (63, 64). This evidence concerns the gene IL15 and psoriasis.