Heterogeneity of thymic dendritic cells.

Thymus is the site of generation and selection of T-lymphocytes. It also contains phenotypically and functionally distinct dendritic cell (DC) populations, including conventional DC (cDC) and plasmacytoid DC (pDC). Thymic cDC are heterogeneous and contain two subsets: a major subset derived from the precursors within thymus, and a minor subset presumably of extrathymic origin. Increasing evidence suggest that thymic cDC can cross-present self-antigens to developing thymocytes and play an important role in thymocyte negative selection and central tolerance induction. Thymic pDC can produce type-I interferon upon appropriate activation. However, their role in a steady state thymus is currently unclear.