Investigation into the prevalence of a novel dendritic‐like cell subset in vivo

A novel dendritic‐like cell subset termed L‐DC was recently identified in murine spleen based on marker expression of a homogeneous cell population derived from long‐term culture of neonatal spleen. The function of L‐DC is distinct from other splenic dendritic and myeloid cell subsets because of their high endocytic capacity and their ability to cross‐present antigen to CD8⁺ T cells. This paper shows the subset to be unique to spleen and blood, with a similar, but possibly functionally distinct subset also present in bone marrow. The prevalence of the subset is low; ~6% of all dendritic and myeloid cells in the spleen and ~5% in blood. However, they are a distinct cell type on the basis of marker expression, and endocytic and T‐cell stimulatory capacity. Attempts to identify an enriched population of these cells in mutant mouse strains with reported increases in myelopoiesis showed either a lack of L‐DC or an altered phenotype reflective of the phenotype of the mouse strain.