We assessed gene expression in tissue macrophages from various mouse organs. The diversity in gene expression among different populations of macrophages was considerable. Only a few hundred mRNA transcripts were selectively expressed by macrophages rather than dendritic cells, and many of these were not present in all macrophages. Nonetheless, well-characterized surface markers, including MerTK and FcγR1 (CD64), along with a cluster of previously unidentified transcripts, were distinctly and universally associated with mature tissue macrophages. TCEF3, C/EBP-α, Bach1 and CREG-1 were among the transcriptional regulators predicted to regulate these core macrophage-associated genes. The mRNA encoding other transcription factors, such as Gata6, was associated with single macrophage populations. We further identified how these transcripts and the proteins they encode facilitated distinguishing macrophages from dendritic cells.
Bibliographical noteFunding Information:
We thank our colleagues of the ImmGen Project consortium; V. Jojic, J. Ericson, S. Davis and C. Benoist for contributions; eBioscience and Affymetrix for material support of the ImmGen Project; and M. Colonna (Washington University School of Medicine) for monoclonal antibodies (including anti-Siglec-H) and other reagents. Supported by the National Institute of Allergy and Infectious Diseases of the US National Institutes of Health (R24 AI072073 to fund the ImmGen Project, spearheaded by C. Benoist), the US National Institutes of Health (R01AI049653 and R01AI061741 to G.J.R.; P50GM071558-03 and R01DK08854 to A.M.; and5T32DA007135-27 to A.R.M.) and the American Heart Association (10POST4160140 to E.L.G.).