Oestrogen treatment depletes extrathymic T cells from intestinal lymphoid tissues.

Different lineages of thymic and extrathymic T cells are found in the epithelial layer and in the lamina propria of the small and large intestine of euthymic and athymic mice. A single subcutaneous injection of oestradiolvalorat (Progynon-Depot-10, Schering, Berlin, Germany) into athymic mice led to a dose-dependent depletion of extrathymic T cells from the intraepithelial and lamina propria compartments of the small and large intestine. TCR alpha beta and TCR gamma delta, CD4+ and CD8 alpha+ T cell subsets were affected. The depletion of intraepithelial, extrathymic T cells by oestradiol treatment was striking. Oestrogen, therefore, has an effect not only on genital mucous membranes, but also on the large, diffuse lymphoid tissues of the gut, in that it selectively depletes the intestinal, extrathymic T-cell subsets.