Intraepithelial lymphocytes (IELs) represent the first line of lymphocyte defense against the intestinal bacteria.
Although previous studies have demonstrated a protective role of IELs in the development of colitis, the data supporting a regulatory role for IELs are limited.
The objective of this study was to examine the suppressive activity of IELs in vitro and in vivo using a mouse model of chronic small and large bowel inflammation.
Adoptive transfer of CD8α(+) IELs isolated from small intestines of wild-type (WT) mice into TCR βxδ-deficient (TCR βxδ(-/-)) recipients did not prevent or delay the onset of the disease induced by WT CD4(+)CD45RB(high) T cells.
On the contrary, we observed a more rapid onset of wasting and clinical signs of intestinal inflammation when compared with animals injected with CD4(+)CD45RB(high) T cells alone.
Histopathological scores of small and large bowel did not differ significantly between the two groups.
Transfer of IELs alone did not produce any pathological changes. Real-time PCR analysis of intestinal tissues showed up-regulation of message for T(h)1- and macrophage-derived cytokines in colon and small bowel.
Using Foxp3-GFP reporter mice, we were unable to detect any Foxp3(+) cells within the CD8α(+) IELs but did find a small population of Foxp3(+)CD4(+) IELs in the small and large bowel.
Using in vitro suppression assay, we found that neither TCRαβ(+)CD8αα(+), TCRαβ(+)CD8αβ(+) nor TCRγδ(+)CD8αα(+) IELs were capable of suppressing CD4(+) T-cell proliferation.
Taken together, our data do not support an immunoregulatory role for CD8α(+) IELs in a mouse model of small and large bowel inflammation.
2010-12-14
Eng.
International immunology
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, 1501 Kings Highway, PO Box 33932, Shreveport, LA 71130-3932, USA. dostan [at] lsuhsc.edu
Int Immunol. 2010 Dec;22(12):927-39
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