Polarized Production of T-Helper Cell Type 1 Cells in Peyer’s Patches in Crohn’s Disease

Although Peyer's patches (PPs) serve as important antigen-sampling sites for the immune system, surprisingly little attention has been paid to their associations with the onset of Crohn's disease (CD) as antigen entry sites. To examine the immunological events in PPs, we performed functional and phenotypical studies on PP cells, the lamina propria cells in the colonic mucosa and peripheral blood mononuclear cells (PBMC) in inflammatory bowel disease.The subjects were 9 children and adolescents with active CD, 9 with inactive CD, 11 with active ulcerative colitis (UC), and 22 normal controls.The cytokine profile in PPs and lamina propria was performed through Elispot assay and RT-PCR. PP mononuclear cells and PBMC from the subjects were analyzed by flow cytometry using monoclonal antibodies to interferon-gamma and interleukin-4, and CC chemokine receptors (CCR) 4 and 5.Th1 together with Tc1 cells were dominant in PPs in the active phase of CD, but not in inactive CD, UC, or normal controls. They did not actually produce interferon-gamma, however they have abundant mRNA of the cytokine. Substantial levels of CCR5 ligands, MIP-1alpha and RANTES mRNA were found in the inflamed intestinal mucosa in CD.It is conceivable that PPs in the terminal ileum in CD may initially sample luminal antigens where Th1-type memory cells are activated which migrate to the peripheral intestinal mucosa. Those immunological changes may not be related to the etiology of UC.