Single-cell immune profiling reveals novel thymus-seeding populations, T cell commitment, and multi-lineage development in the human thymus

SummaryT cell development in the mouse thymus has been studied rather extensively; in contrast, strikingly little is known regarding T cell development in the human thymus. To close this knowledge gap, we used a combination of single-cell techniques and functional assays to perform deep immune profiling of human T cell development, focusing on the initial stages of pre-lineage commitment. We identified three thymus-seeding progenitor populations that also have counterparts in the bone marrow. In addition, we found that the human thymus physiologically supports the development of monocytes, dendritic cells, and NK cells, as well as limited development of B cells. These results are an important step towards monitoring and guiding regenerative therapies in patients following hematopoietic stem cell transplantation.