Mucosal T lymphocyte numbers are selectively reduced in integrin alpha(E) (CD103)-deficient mice

The mucosal lymphocyte integrin alpha(E)(CD103)beta(7) is thought to be imp ortant for intraepithelial lymphocyte (IEL) localization or function, We cl oned the murine integrin gene encoding alpha(E), localized it to chromosome Il, and generated integrin alpha(E)-deficient mice, In alpha(E)(-/-) mice, intestinal and vaginal IEL numbers were reduced, consistent with the known binding of alpha(E)beta(7) to E-cadherin expressed on epithelial cells. Ho wever, it was surprising that lamina propria T lymphocyte numbers were dimi nished, as E-cadherin is not expressed in the lamina propria, In contrast, peribronchial, intrapulmonary, Peyer's patch, and splenic T lymphocyte numb ers were not reduced in alpha(E)-deficient mice. Thus, alpha E beta(7) was important for generating or maintaining the gut and vaginal T lymphocytes l ocated diffusely within the epithelium or lamina propria but not for genera ting the gut-associated organized lymphoid tissues. Finally, the impact of alpha(E) deficiency upon intestinal IEL numbers was greater at 3-4 wk of li fe than in younger animals, and affected the TCR alpha beta(+) CD8(+) T cel ls more than the gamma delta T cells or the TCR alpha beta(+) CD4(+)CD8(-) population. These findings suggest that alpha(E)beta(7) is involved in the expansion/recruitment of TCR alpha beta(+) CD8(+) IEL following microbial c olonization. Integrin alpha(E)-deficient mice will provide an important too l for studying the role of alpha(E)beta(7) and of alpha(E)beta(7)-expressin g mucosal T lymphocytes in vivo.