Development of Dendritic Cells from GM‐CSF^-/-Mice invitro: GM‐CSF Enhances Productionand Survival of Cells

Abstract

The production of dendritic cells (DC) from haemopoietic progenitors maintained in long term stroma-dependent cultures (LTC) of spleen or bone marrow (BM) occurs independently of added granulocyte/macrophage colony stimulating factor (GM-CSF). The possibility that cultures depend on endogenous GM-CSF produced in low levels was tested by attempting to generate LTC from spleen and BM of GM-CSF-/-mice. Multiple cultures from GM-CSF-/-and wild type mice were established and compared for cell production. GM-CSF-/-LTC developed more slowly, but by 16 weeks produced cells resembling DC in numbers comparable to wild type cultures. LTC maintained distinct populations of small and large cells, the latter resembling DC. Cells collected from GM-CSF-/-LTC were capable antigen presenting cells (APC) for T cell stimulation and morphologically resembled DC. Large cells expressed the CD11b, CD11c, CD86, 33D1 and Dec-205 markers of DC. Addition of GM-CSF to GM-CSF-/-LTC increased the proportion of large, mature DC present in culture. Stromal cells from GM-CSF-/-LTC could support the differentiation of DC from early progenitors maintained in LTC without addition of GM-CSF. However, GM-CSF is not a critical factor in theinvitrogeneration of DC from progenitors. It can, however, substitute for stromal cells in increasing the survival of mature DC.

Mast Cells Condition Dendritic Cells to Mediate Allograft Tolerance

“…It is known that the Csf2 −/− mice have ~20% reduction in the overall number of DCs (Kingston et al, 2009; Ni and O’Neill, 2001) and that GM-CSF induces a survival program in DCs protecting them from apoptosis (Chen et al, 2007). To address whether GM-CSF impacted survival of DCs in vivo, we sorted graft-derived DCs from the dLN.…”

Hematopoiesis leading to a diversity of dendritic antigen‐presenting cell types

“…Gene expression studies have shown that LTC‐DCs express genes encoding several cell surface molecules expressed by DCs 101 , 102 . LTCs are distinct from other in vitro cultures for DC production in that stromal cells support DC production without addition of exogenous inflammatory cytokines, reflecting the capacity of the spleen stromal cells to support DC hematopoiesis 103 . The continual production of immature myeloid DCs in LTCs led to the hypothesis that hematopoietic stem or progenitor cells are maintained within LTCs 104 , 105 .…”

Myelopoiesis related to perinatal spleen

“…As BM is formed around birth and contains approximately the same number of CFC at D2 as does spleen, 2 this late development of DC is consistent with evidence that the most common spleen DC subsets, including cDC and pDC, are not endogenous to spleen, but develop instead from BM precursors that migrate through blood to spleen, although this does not explain the late development of L-DC. 19 Two previous studies claimed to identify the presence of CD11c + 'DC' in C57BL/6J and BALB/c mice by D1. 20,21 As both studies defined DC on the basis of CD11c expression only, and not MHC-II expression or functional capacity, it is possible that these cells do not reflect DC, but instead represent DC precursors.…”

“…17,18 However, the development of DC within LTC occurs independently of GM-CSF as LTC that produce dendritic-like cells (LTC-DC) can be established from GM-CSFR À/À mice. 19 Flt3-ligand is also essential for the in vivo and in vitro development of conventional (c) DC and plasmacytoid (p) DC. 20,21 As STX3 does not produce either Flt3-ligand or GM-CSF, 22 a role for these cytokines in L-DC production is not supported.…”