a15:0-i15:0 PE is an atypical TLR2 agonist, and its immune signaling strictly depends on the TLR2-TLR1 heterodimer. a15:0-i15:0 PE induces dendritic cells to produce TNFalpha and IL-6, but does not induce the production of IL-10 or IL-12p70. At low doses, a15:0-i15:0 PE resets the activation threshold of immune cells to suppress or regulate immune responses against specific agonists[1].