Complement Component C5a (C5a) is also known as C5, and is a protein fragment released from complement component C5. C5a is an extremely potent proinflammatory mediator, as well as a potent chemotactic factor for neutrophils and other leukocytes. It causes histamine release, increases in vascular permeability, induces several cytokines production from leukocytes, enhances neutrophil-endothelial cell adhesion, and augments the humoral and cell-mediated immune response. C5a is also chemotactic for dendritic cells (DCs), germinal center B cells, and T cells. Thus, anaphalatoxins participate in the recruitment of various leukocytes into sites of inflammation during infection and tissue injury.