Depletion of CD8α+ lymphocytes attenuates CCL28 expression in villus epithelia in rats

To examine the involvement of CD8α+ intraepithelial lymphocytes (IELs) in chemokine expression by villus epithelial cells, villus and crypt fractions were collected by mechanical isolation using a chelating buffer and specific antibodies in CD8α+ cell-depleted rats. A larger population of CD8α+ cells was observed by histochemical evaluation in villus epithelia than in crypt epithelia in rat small intestine, and CCL9 and CCL28 expression was higher in the crypt fraction than in the villus fraction. The mRNA expression of CCL28 in villus fractions isolated from rat small intestinal mucosa was significantly reduced compared to that of CCL9, and was accompanied by CD8α depletion. Using a combined histochemical and flow cytometric approach, CD8αα+ cells were detected in the intraepithelial region of the villus epithelium. Thus, CCL28 expression in villus epithelial cells is partially supported by CD8αα+ cells, and CD8α+ IELs are involved in CCL28 expression.