Review of human dendritic cells: isolation and culture from precursors

There is no single characteristic or marker that identifies a dendritic cell. This review of the methods used for dendritic cell identification stresses that changes occur over the lifetime and changing functional status of the cell. Human dendritic cell populations have been obtained from adult peripheral blood, umbilical cord blood, bone marrow, thymus, and monocytes as starting substrates. Most recently dendritic cell populations have been grown from separated hematopoietic precursors, suggesting that there is a common granulocyte-monocyte-dendritic cell progenitor. Whether monocytes and dendritic cells can be modulated back and forth remains an open question. Granulocyte-monocyte colony stimulating factor (GM-CSF) appears to be critical to the development and function of these enriched and cultured cells. The characteristics of the cells produced by these various methods are tabulated. Important to the understanding of Langerhans cell biology is the variation in CD1 expression under different circumstances.