Inflammasome induction in human MDSC interferes with their suppressor function. Human MDSCs were generated from donor PBMCs. (A) IL-1β ELISA of supernatants from MDSCs treated with 0.2 µg/mL LPS for 3 hours followed by 2 mM ATP for 1 hour prior to harvest. Data are representative of 2 independent experiments. (B) Representative histograms of responder PBMCs labeled with CellTrace Violet (Life Technologies) in the presence of cultured human MDSCs from unrelated donors indicated by solid line. Dotted line indicates no-MDSC proliferation control, gray histogram indicates PBMCs alone (no CD3ε or MDSCs). No Stim represents the alloresponse against MDSCs with no anti-CD3ε. Stim indicates addition of anti-CD3ε microbeads (2:1) + IL-2 (100 U/mL) to demonstrate MDSC suppression of T-cell activation. Stim + Infl. Tx’d indicates MDSCs have been treated for inflammasome activation prior to plating with anti-CD3ε microbeads + IL-2. (C) Aggregate data show percent division of responding CD8 and CD4 T cells. Data represent responses from 3 unrelated PBMC donors and are representative of 2 independent experiments.