Spleen as a Site for Hematopoiesis of a Distinct Antigen Presenting Cell Type

Abstract

While spleen and other secondary tissue sites contribute to hematopoiesis, the nature of cells produced and the environment under which this happens are not fully defined. Evidence is reviewed here for hematopoiesis occurring in the spleen microenvironment leading to the production of tissue-specific antigen presenting cells. The novel dendritic-like cell identified in spleen is phenotypically and functionally distinct from other described antigen presenting cells. In order to identify these cells as distinct, it has been necessary to show that their lineage origin and progenitors differ from that of other known dendritic and myeloid cell types. The spleen therefore represents a distinct microenvironment for hematopoiesis of a novel myeloid cell arising from self-renewing hematopoietic stem cells (HSC) or progenitors endogenous to spleen.

Novel splenic antigen-presenting cells derive from a Lin−c-kitlo progenitor

“…Splenic progenitors described here are distinct in relation to previously described common dendritic progenitors and myeloid dendritic progenitors, which have been found only in BM and not spleen [19,20]. Previous studies identified immediate precursors of cDC in spleen as CD11c int CD43 int Sirp␣ int cells, which are not self-renewing [21].…”

Extramedullary hematopoiesis: Elucidating the function of the hematopoietic stem cell niche (Review)

“…A study has suggested that splenic niches may support the development of certain distinct, dendritic-like antigen-presenting cells (52). Although such experiments utilizing animal models have provided useful results and hypotheses, further studies should be conducted in order to identify specific differences in the characteristics and differentiation patterns of HSCs between human bone marrow and splenic EMH.…”

Development of Two Distinct Dendritic-Like APCs in the Context of Splenic Stroma

“…A novel dendritic-like cell type has been described in spleen, namely “L-DC” (O’Neill et al, 2011; Tan et al, 2011). Studies to identify a progenitor of L-DC have revealed a subset of lineage (Lin) − c-kit lo cells in adult and neonatal spleen reflecting hematopoietic stem/progenitor cells (HSPC) (Tan et al, 2010; Tan and O’Neill, 2012; Periasamy et al, 2013).…”