Cleaved by the lysosomal asparaginyl endopeptidase (legumain; δ-secretase), the N-terminally acetylated 28-residue peptide Tα1 gets released [4]. Tα1 plays a significant role in activating and regulating various cells of the immune system [5], e.g., by stimulating toll-like receptor (TLR)-2 and TLR-9 on myeloid and plasmacytoid dendritic cells (DCs)