CD4 and acute kidney injury: To determine whether an LPS-induced AKI stimulates the IL-18/IL-18R signaling pathway via CD4+ T cells and macrophages, we measured the mRNA expressions of IL-18, IL-18Rα and IL-18Rβ in isolated splenic CD4+ T cells and F4/80+ cells using fluorescence-activated cell sorting (FACS) in wild-type (WT) C57BL/6 mice before and after LPS injection (Figure 1).