Subsets of human dendritic cell precursors express different toll-like receptors and respond to different microbial antigens.
Toll-like receptors (TLRs) are ancient microbial pattern recognition receptors highly conserved from Drosophila to humans. To investigate if subsets of human dendritic cell precursors (pre-DC), including monocytes (pre-DC1), plasmacytoid DC precursors (pre-DC2), and CD11c(+) immature DCs (imDCs) are developed to recognize different microbes or microbial antigens, we studied their TLR expression and responses to microbial antigens. We demonstrate that whereas monocytes preferentially express TLR 1, 2, 4, 5, and 8, plasmacytoid pre-DC strongly express TLR 7 and 9. In accordance with these TLR expression profiles, monocytes respond to the known microbial ligands for TLR2 (peptidoglycan [PGN], lipoteichoic acid) and TLR4 (lipopolysaccharide), by producing tumor necrosis factor (TNF)-alpha and interleukin (IL)-6. In contrast, plasmacytoid pre-DCs only respond to the microbial TLR9-ligand, CpG-ODNs (oligodeoxynucleotides [ODNs] containing unmethylated CpG motifs), by producing IFN-alpha. CD11c(+) imDCs preferentially express TLR 1, 2, and 3 and respond to TLR 2-ligand PGN by producing large amounts of TNF-alpha, and to viral double-stranded RNA-like molecule poly I:C, by producing IFN-alpha and IL-12. The expression of distinct sets of TLRs and the corresponding difference in reactivity to microbial molecules among subsets of pre-DCs and imDCs support the concept that they have developed through distinct evolutionary pathways to recognize different microbial antigens.
Kadowaki
N
N
DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA 94304, USA.
Ho
S
S
Antonenko
S
S
Malefyt
R W
RW
Kastelein
R A
RA
Bazan
F
F
Liu
Y J
YJ
D015415:Biomarkers; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D029721:Drosophila Proteins; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000276:immunology; D011956:Receptors, Cell Surface / Q000235:genetics*; D013211:Staphylococcus aureus / Q000276:immunology; D051194:Toll-Like Receptor 1; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051199:Toll-Like Receptor 7; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors
D015415:Biomarkers; C408982:CPG-oligonucleotide; D016207:Cytokines; D029721:Drosophila Proteins; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; C495348:TLR7 protein, human; C495371:TLR9 protein, human; D051194:Toll-Like Receptor 1; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051199:Toll-Like Receptor 7; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors