Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Since direct injection of naked mRNA induces an immune response, we tested the capacity of RNA to signal danger. We show here that mRNA molecules that are protected from immediate degradation either through interaction with cationic proteins (<jats:italic>trans</jats:italic> protection) or through chemical modification of the phosphodiester backbone (phosphorothioate RNA; <jats:italic>cis</jats:italic> protection) act as sequence‐independent danger signals on mouse DC. As opposed to CpG DNA, the <jats:italic>cis</jats:italic>‐stabilized RNA is degraded in a few minutes, does not activate B cells and, in contrast to double‐stranded RNA, requires MyD88 for activation of the DC. We postulate that phosphorothioate RNA, which mimics <jats:italic>trans</jats:italic>‐stabilized RNA, is a new PAMP.</jats:p>