Intestinal Epithelial Cell Line Induction of T Cell Differentiation from Bone Marrow Precursors

The mechanism whereby the intestinal microenvironment promotes T cell development in the absence of the thymus is unknown. We show that the murine intestine-derived epithelial cell line, MODE-K, can induce T cell differentiation marker expressionin vitroon bone marrow (BM) T cell precursors. Three-color flow cytometry analysis of T-cell-depleted C3H BM mononuclear cells (MNC) after 4 days of coculture on monolayers of MODE-K indicated that ∼25% of MNC expressed CD3 and TCRαβ. Of these CD3+cells, 36% were CD3loCD4−CD8−double negative (DN), 34% were CD3loCD4+CD8αβ+double positive (DP), and the remainder were CD3hiCD4+CD8−or CD3hiCD4−CD8αβ+single positive (SP). In addition, the T cells which developed in coculture with MODE-K expressed the early T cell differentiation marker CD24 (heat-stable antigen). These T cell subsets did not develop when BM was cocultured with the LTA fibroblast cell line or in medium alone. Interestingly, preventing cell contact between MODE-K and BM by culturing in Transwell plates did not interfere with the development of T cells expressing the DN, DP, or SP phenotypes. Double-positive T cells did not develop if splenic MNC were cocultured with MODE-K. These results suggest that the intestinal epithelial environment can induce and support the T cell development from bone marrow precursors.