IL21 and collagenous colitis: In humans, a recent study used Luminex assays to assess mucosal cytokines in microscopic colitis patients, where 10 analytes were examined in 10 control patients, 3 UC patients, and 25 microscopic colitis patients [25]; increases in IL-6 and IL-21 protein were detected in collagenous colitis, but no increases in any analytes were detected in UC tissues, due most likely to the small number of patients studied.