Clinical science
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We investigated whether activation of circulating DCs (dendritic cells) or levels of Flt3L (FMS-like tyrosine kinase 3 ligand) and GM-CSF (granulocyte/macrophage colony-stimulating factor), haematopoietic growth factors important for DC differentiation, could account for reduced blood DC numbers in CAD (coronary artery disease) patients. Concentrations of Flt3L and GM-CSF were measured in plasma from CAD patients (n = 15) and controls (n = 12). Frequency and phenotype of mDCs (myeloid dendritic cells) and pDCs (plasmacytoid dendritic cells) were analysed by multicolour flow cytometry in fresh blood, and after overnight incubation with TLR (Toll-like receptor)-4 or -7 ligands LPS (lipopolysaccharide) or IQ (imiquimod). ⋯ In conclusion, our results suggest that reduced blood DC counts in CAD are, at least partly, due to impaired DC differentiation from bone marrow progenitors. Decreased levels of mDCs are presumably also explained by activation and subsequent migration to atherosclerotic plaques or lymph nodes. Although mDCs are functioning normally, pDCs from patients appeared to be both numerically and functionally impaired.