Related Experiment Videos
CpG motifs in bacterial DNA trigger direct B-cell activation
1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
Nature
|April 6, 1995
Summary
Bacterial DNA containing unmethylated CpG dinucleotides activates immune cells. This discovery reveals a potential evolutionary link and new applications for immune adjuvants.
Area of Science:
- Immunology
- Microbiology
- Genetics
Background:
- Vertebrate genomes exhibit 'CpG suppression', meaning unmethylated CpG dinucleotides are rare.
- Conversely, bacterial and viral DNA frequently contain unmethylated CpG motifs.
Purpose of the Study:
- To investigate the immune stimulatory effects of unmethylated CpG dinucleotides found in microbial DNA.
- To determine the specific DNA motifs and conditions required for optimal B-cell activation.
Main Methods:
- Treatment of murine B cells with bacterial DNA and synthetic oligodeoxynucleotides containing unmethylated CpG motifs.
- Assessment of B-cell proliferation and immunoglobulin secretion in vitro and in vivo.
- Analysis of the structural requirements for CpG-mediated B-cell activation.
Main Results:
- Unmethylated CpG dinucleotides in bacterial DNA and synthetic oligonucleotides potently activate murine B cells.
- B-cell activation is enhanced by co-stimulation via the antigen receptor.
- A specific DNA motif (CpG flanked by purines and pyrimidines) is optimal for B-cell activation, inducing cell cycle entry in over 95% of spleen B cells.
- These findings suggest an evolutionary link between microbial DNA recognition and CpG suppression in vertebrates.
Conclusions:
- Unmethylated CpG motifs in microbial DNA act as potent immune activators, specifically stimulating B cells.
- The findings have implications for the use of antisense oligonucleotides and suggest potential applications for CpG oligonucleotides as immune adjuvants.