Spleen as a site for myelopoiesis
Bone marrow is the main site for hematopoiesis in adults, although increasing reports identify hematopoiesis occurring in other tissue sites. While spleen and other extramedullary sites contribute to hematopoiesis, the nature of cells produced, and the conditions under which this happens, are not yet fully defined.
This study addresses extramedullary myelopoiesis occurring in spleen leading to the development of a novel dendritic-like cell cell type which was discovered in this lab which is unique in terms of its phenotype and immune function. This project considers the hypothesis that extramedullary hematopoiesis may mediate the production of tissue-specific antigen presenting cells like dendritic cells which have site-specific function in both innate and adaptive immunity.
In order to identify such subsets as distinct it is necessary to show that their lineage origin differs from that of other common dendritic cells and myeloid subsets. Experiments are underway to identify the hematopoietic progenitors of this novel cell type in spleen and the relationship between those progenitors and hematopoietic stem cells. The conditions under which hematopoiesis occurs are being investigated using mutant mouse models which have genetically determined defects affecting hematopoiesis.