CCL2 and acute respiratory distress syndrome: Alternatively, when basal levels of cytokine production were measured between these three groups, no IL-10, IL-12, IFN- γ, or MCP-1 was detected, but cells cultured with the ARDS mouse BAL fluid had significantly less TNF-α production (2.7 pg/mL) compared to cells cultured with ARDS mouse BAL fluid in which the sPD-1 precipitated out (52.38 pg/mL, p = 0.002, Fig. 3b).