Thymic nurse cells support CD4-CD8+ thymocytes to differentiate into CD4+CD8+ cells.

Thymic nurse cells (TNCs) represent a unique microenvironment in the thymus for T cell maturation. In order to investigate the role of thymic nurse cells during T cell differentiation, a TNC clone, RWTE-1, which formed a typical complex with fetal thymocytes in vitro was established from normal Wistar rat. Hanging drop culture method was applied to reveal the interaction between TNCs and thymocytes. Our result revealed that eighty percent of immature CD4(-)CD8(+) cells differentiated into CD4(+)CD8(+) cells after a 12-hour hanging drop culture with RWTE-1. However, in a 12-hour culture of immature CD4(-)CD8(+) cells with or without RWTE-1 supernatant, only 30% of the cells differentiated into CD4(+)CD8(+) cells spontaneously. This observation led to the conclusion that RWTE-1 cell has the capacity to facilitate immature CD4(-)CD8(+) thymocytes to differentiate into CD4(+)CD8(+) T cells by direct interaction.