ARG1 and ovarian carcinoma: Arginase-1 (ARG1)-carrying exosomes accelerate ovarian cancer growth by suppressing T-cells Phosphatidylserine in ascites inhibits T-cell activity and Fas ligand induces the apoptosis of T-cells [41,42,43] Labani-Motlagh et al. reported that phosphatidylserine, natural-killer receptor group 2, member D (NKG2D) and DNX accessory molecule-1 (DNAM-1) ligands in ascites-derived exosomes inhibited NK cell activity, resulting in immune suppression [40].