Three populations of mouse lymph node dendritic cells with different origins and dynamics.

We have identified three distinct populations of mouse lymph node dendritic cells (DC) that differ in their capacity to uptake Ag delivered by different routes, and in their dynamics. The "I-DCs" are large cells that resemble the interdigitating cells and have a mature phenotype and a slow turnover. They derive from the regional tissues. The "sm-DCs" and "sI-DCs" are smaller (hence s-DC), have a more immature phenotype and a rapid turnover. The sI-DC phenotype, including CD8alpha expression suggests a lymphoid-related origin. The sI-DC population is expanded 100-fold after an in vivo flt3 ligand treatment. The sm-DC phenotype suggests a myeloid-related origin. Interestingly, sm-DCs can acquire i.v. injected macromolecules in less than 30 min after injection. They may, therefore, play an important role in the immune response against blood Ags.