A canine macrophage cell line that can be polarized provides a model for canine macrophage differentiation.

Monocyte-like cell lines are valuable models for studying macrophage biology, yet a well-characterized canine macrophage model has been lacking. The canine histiocytic sarcoma-derived cell line 030D was assessed for its macrophage polarization potential by stimulation with IFN-γ + LPS (M1) or IL-4 (M2), or no additives (M0) and characterized for morphology, immunophenotype, marker gene expression, and phagocytic capacity. 030D M1 macrophages expressed higher levels of the surface markers CD32, CD40, CD80, CD83, CD86 and MHC II than 030D M2 macrophages. qPCR analysis showed higher expression of pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, IL-12p35/40, IL-23p19, COX2, CCL2, and CCR7), anti-inflammatory cytokines TGF-β and IL-10, as well as higher expression of LOX-1, LXN, and arginase-1 by 030D M1 macrophages compared to 030D M2 macrophages. Conversely, established M2 markers MS4A2 and CD206 were significantly higher in 030D M2 macrophages compared to 030D M1 macrophages. Functionally, 030D M1 macrophages displayed higher phagocytic activity than 030D M2 macrophages. Comparison of 030D-derived macrophages with primary canine monocyte-derived macrophages (MDMs) demonstrate that both models, with the exception of TGF-β and IL-10, resemble each other in the studied parameters. Thus, the 030D cell line provides a highly accessible and validated tool for studying canine macrophage biology and immune responses.