Gene expression analysis of intestinal intraepithelial lymphocytes derived from mice fed a food antigen or functional food factors.

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We focused on intestinal intraepithelial lymphocytes (IEL), which are a kind of T cells residing in intestinal epithelia, and the gene expression in IEL derived from mice fed a food antigen was analyzed. When ovalbumin-specific T-cell receptor transgenic mice (DO11.10 mice) were fed a diet containing egg white proteins (EW-diet) ad libitum for 3 days, increase in the number of CD4^+ IEL among whole IEL and alteration of cell-surface molecule expression on IEL were observed. DNA microarray analysis of IEL derived from mice fed the EW-diet showed the increased expression of 98 genes and decreased expression of 24 genes. Genes with increased expression contained cell-cycle related genes and immune-related genes including interleukin-10 (IL-10). IEL derived from the EW-fed mice showed increased secretion of IL-10 compared to the control IEL. IL-10 gene expression was significantly observed in CD4^+ IEL subset without in vitro stimulation, and the expression level was higher than CD4^+ T cells from other gut-associated lymphoid tissues. Since IL-10 gene expression per CD4^+ IEL was not increased by feeding the EW-diet, the increased cell number of CD4^+ IEL subsets was suggested to be responsible for the increased gene expression of IL-10 in IEL from the EW-fed mice. When the gene expression profiles were compared among IEL subsets, the expression of granzyme A was shown to be much less in CD4^+ IEL than in other IEL subsets. Since IL-10 is a cytokine important for the immune-suppressive function of a kind of regulatory T cells, CD4^+ IEL may have a function in regulating the immune responses in intestinal mucosa, and the regulatory function of IEL would be increased by feeding a food antigen.