C5AR1 and Sepsis: During the onset of experimental sepsis in rodents, up-regulated expression of C5aR was found in whole organs including lung, thymus, kidney, liver, and heart (Riedemann et al., 2002b) (Riedemann et al., 2003c), though CLP-induced C5aR level on neutrophils was reduced (Guo et al., 2003).