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ABSTRACT: Background
Major histocompatibility complex (MHC) class II molecules play crucial roles in immune activation by presenting foreign peptides to antigen-specific T helper cells and thereby inducing adaptive immune responses. Although adaptive immunity is a highly effective defense system, it takes several days to become fully operational and needs to be triggered by danger-signals generated during the preceding innate immune response. Here we show that MHC class II molecules synergize with Toll-like receptor (TLR) 2 and TLR4 in inducing an innate immune response.Methodology/principal findings
We found that co-expression of MHC class II molecules and TLR2 or TLR4 in human embryonic kidney (HEK) cells 293 leads to enhanced production of the anti-microbial peptide human-beta-defensin (hBD) 2 after treatment with TLR2 stimulus bacterial lipoprotein (BLP) or TLR4 ligand lipopolysaccharide (LPS), respectively. Furthermore, we found that peritoneal macrophages of MHC class II knock-out mice show a decreased responsiveness to TLR2 and TLR4 stimuli compared to macrophages of wild-type mice. Finally, we show that MHC class II molecules are physically and functionally associated with TLR2 in lipid raft domains of the cell membrane.Conclusions/significance
These results demonstrate that MHC class II molecules are, in addition to their central role in adaptive immunity, also implicated in generating optimal innate immune responses.
SUBMITTER: Frei R
PROVIDER: S-EPMC2808354 | biostudies-literature | 2010 Jan
REPOSITORIES: biostudies-literature
Frei Remo R Steinle Johanna J Birchler Thomas T Loeliger Susanne S Roduit Caroline C Steinhoff Dirk D Seibl Reinhart R Büchner Katja K Seger Reinhard R Reith Walter W Lauener Roger P RP
PloS one 20100120 1
<h4>Background</h4>Major histocompatibility complex (MHC) class II molecules play crucial roles in immune activation by presenting foreign peptides to antigen-specific T helper cells and thereby inducing adaptive immune responses. Although adaptive immunity is a highly effective defense system, it takes several days to become fully operational and needs to be triggered by danger-signals generated during the preceding innate immune response. Here we show that MHC class II molecules synergize with ...[more]