Expression of pT mRNA in a Committed Dendritic Cell Precursor in the Human Thymus

Abstract

We have characterized dendritic cell precursors (pre-DC) in the human thymus. These CD1a−CD3−CD4+CD8−cells express high levels of interleukin-3R (IL-3R) on the membrane and are able to develop into mature DC upon culture with IL-3 and CD40 ligation. The DC precursors are predominantly located in the thymic medulla. Interestingly, the pre-DC express pT mRNA, which is also present in CD1a+CD3−CD4+ CD8−pre-T cells. Yet, the pre-DC lack expression of recombination activating gene-1 mRNA and fail to develop into T cells in appropriate assays. The thymic pre-DC are very similar to the recently characterized pre-DC found in the T cell areas of the tonsil, and it is suggested that these pre-DC populations are of lymphoid origin.