Lower SCD expression in dendritic cells compared to macrophages leads to membrane lipids with less mono-unsaturated fatty acids

Macrophages and dendritic cells originate from a common myeloid precursor. Although several studies compared transcriptional profiles of these cells, not a single study compared their lipid profiles. Therefore, we measured and compared fatty acid (FA) and phospholipid (PL) species composition of granulocyte/macrophage colony-stimulating factor (GM-CSF) plus interleukin 4 (IL-4) and macrophage colony-stimulating factor (M-CSF) differentiated monocytes isolated from healthy volunteers. We found that these two cell types prominently differ in their FA composition. Dendritic cells (DCs) contain lower proportions of C16 and C18 mono-unsaturated FAs, but higher proportions of C20 and C22 poly-unsaturated fatty acids (PUFAs) than phagocytic macrophages. Analysis of PL species profiles revealed that GM-CSF/IL-4 differentiated cells have increased amounts of longer and more desaturated phospatidylethanolamine (PE) and phosphatidylserine (PS) species, but lower amounts of shorter and less desaturated PE and PS species than M-CSF differentiated cells. These cell type specific lipid profiles can be attributed to a differential expression and activity of stearoyl-CoA desaturase (SCD). Taken together, our results show that GM-CSF/IL-4 compared to M-CSF differentiated monocytes have less mono-unsaturated FA and PL species, which are due to lower SCD activity observed in DCs.