Аннотация:A bstract : Dendritic cells (DCs) are professional antigen‐presenting cells which both initiate adaptive immune responses and control tolerance to self‐antigens. It has been suggested that these different effects on responder cells depend on subsets of DCs arising from either myeloid or lymphoid hematopoietic origins. In this model, CD8α + Mac‐1 − DCs are supposed to be of lymphoid while CD8α − Mac‐1 + DCs are supposed to be of myeloid origin. Here we summarize our findings that both CD8α + and CD8α − DCs can arise from clonogenic common myeloid progenitors (CMPs) in both thymus and spleen. Therefore CD8a expression on DCs does not indicate a lymphoid origin and differences among CD8α + and CD8α − DCs might rather reflect maturation status than ontogeny. On the basis of transplantation studies, it seems likely that most of the DCs in secondary lymphoid organs and a substantial fraction of thymic DCs are myeloid‐derived.
