Abstract

We have examined the potential to generate bona fide macrophages (MO) from conditionally immortalised murine bone marrow precursors. MO can be derived from Hoxb8 conditionally immortalised macrophage precursor cell lines (MOP) using either M-CSF or GM-CSF. When differentiated in GM-CSF (GM-MOP) the resultant cells resemble GM-CSF bone marrow-derived dendritic cells (BMDC) in morphological phenotype, antigen phenotype and functional responses to microbial stimuli. In spite of this high similarity between the two cell types and the ability of GM-MOP to effectively present antigen to a T-cell hybridoma, these cells are comparatively poor at priming the expansion of IFN-gamma responses from naive CD4(+) T cells. The generation of MOP from transgenic or genetically aberrant mice provides an excellent opportunity to study the inflammatory role of GM-MOP, and reduces the need for mouse colonies in many studies. Hence differentiation of conditionally immortalised MOPs in GM-CSF represents a unique in vitro model of inflammatory monocyte-like cells, with important differences from bone marrow-derived dendritic cells, which will facilitate functional studies relating to the many 'sub-pheno-types' of inflammatory monocytes.