ODN TTAGGG (ODN A151) Toll-like receptor 9 (TLR9) recognizes specific unmethylated CpG oligonucleotide (ODN) sequences that distinguish microbial DNA from mammalian DNA. Recent studies suggest the existence of DNA sequences that can neutralize the stimulatory effect of CpG ODNs [1]. These sequences are characterized by three consecutive Gs downstream of a C or A, addition of a fourth G (G-tetrads) increases the inhibitory capability. The most potent inhibitory sequences are (TTAGGG)4 found in mammalian telomeres [2] and ODN 2088 which derives from a stimulatory ODN by replacement of 3 bases [3]. Inhibitory ODNs act by disrupting the colocalization of CpG ODNs with TLR9 in endosomal vesicles without affecting cellular binding and uptake. Synonym: ODN A151 Specificity: human TLR9 antagonist Working concentration: 100 nM - 10 µM Solubility: 2.5 mg/ml in water ODN TTAGGG (ODN A151) sequence 5’- ttt agg gtt agg gtt agg gtt agg g -3’ (25 mer) Note: Bases are phosphorothioate (nuclease resistant). Quality control: - Biological activity is tested using HEK-Blue™ TLR9 cells. - The absence of bacterial contamination (endotoxins, peptidoglycans) is controlled using HEK-Blue™ TLR2 and HEK-Blue™ TLR4 cells.