IL22RA2 and inflammatory bowel disease: In addition to the cell surface–associated IL-22 receptor complex, a soluble IL-22–binding receptor (IL-22–binding protein [IL-22BP]) has been identified, and it has been postulated that an increase in the IL-22:IL-22BP ratio in the inflamed colons is the cause of increased systemic IL-22 levels observed in inflammatory bowel disease [31].