The serum levels of IL-17a, sCD40L, Platelet-derived Growth Factor-AA, Macrophage-Derived Chemokine (MDC), and IFNγ were lower in patients with IBD than in the healthy control patients, suggesting a unidirectional flow of cytokines toward the site of the inflammation.18 However, none of the cytokines differed significantly in concentration between the patients with UC and patients with CD. This evidence concerns the gene IL17A and inflammatory bowel disease.