Background: Activated lymphocytes are considered to play a pathogenic role in Crohn's disease (CD) and ulcerative colitis (UC), although only a limited fraction of the gut-residing lymphocytes in these diseases may be pathogenetically involved, due to active recruitment from the peripheral circulation. Our aim was to characterize in situ preactivated lymphocytes in inflammatory bowel disease mucosa by expansion with interleukin-2.
Methods: Flow cytometry was performed on T cells expanded from the colon of patients with CD (7), UC (16), and controls (20), with special reference to T-cell activation markers and adhesion molecules.
Results: In CD a decrease in alpha4beta7 integrin expression was associated with an increase in alphaEbeta7. In UC a similar increase in alphaEbeta7 was observed. Moreover, L-selectin and CD30 were overexpressed on T helper cells in UC versus CD.
Conclusion: These findings indicate different immunopathogenic pathways for CD and UC.