Identification of two subpopulations of purified human blood B cells, CD27- CD23+ and CD27high CD80+, that strongly express cell surface Toll-like receptor 9 and secrete high levels of interleukin-6.
B-cell expression of certain Toll-like receptors (TLRs) is important in linking innate and adaptive immune responses in normal and pathological conditions. The expression of TLR9 plays a role in the recognition of conserved pathogen motifs in a manner that is dependent on B-cell localization, deduced from B-cell phenotype. The nature of TLR9 function is unclear. A first step in unravelling the function of this pattern recognition receptor is to discover the precise nature of the cell types that express TLR9. This study used three-colour flow cytometry to characterize the B lymphocytes from human peripheral blood mononuclear cells (PBMCs) that express TLR9 on the surface. We sorted TLR9-positive B and non-B cells from the PBMC population and detected TLR9 expression on naïve and memory B cells. Moreover, we identified two discrete subpopulations of B cells: CD19(+) CD27(-) CD23(+) cells and CD19(+) CD27(high) CD80(+) cells. These subpopulations expressed high levels of membrane TLR9 and exhibited a strong in vitro response to binding a relevant CpG motif by secreting high levels of interleukin-6 (compared to controls). Our finding that this pattern recognition receptor is expressed on a variety of cell subsets adds to the current understanding of the functional complexity of B-cell membrane TLR9.
Cognasse
Fabrice
F
EFS Auvergne-Loire, Saint-Etienne, France.
Hamzeh-Cognasse
Hind
H
Lafarge
Sandrine
S
Chavarin
Patricia
P
Pozzetto
Bruno
B
Richard
Yolande
Y
Garraud
Olivier
O
D016175:B-Lymphocyte Subsets / Q000276:immunology*; D018122:B7-1 Antigen / Q000097:blood; D002462:Cell Membrane / Q000276:immunology; D002478:Cells, Cultured; D018899:CpG Islands / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology; D015850:Interleukin-6 / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000276:immunology; D017455:Receptors, IgE / Q000097:blood; D051217:Toll-Like Receptor 9 / Q000097:blood*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000097:blood
D018122:B7-1 Antigen; D015850:Interleukin-6; D017455:Receptors, IgE; C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7