CXCR3, CCR5, and CCR6 are chemokine receptors that are responsible for directing cells toward GVHD target organs (liver, lung, intestine) which are the sites of GVHD-associated tissue damage (Wysocki et al., 2005; Varona et al., 2006; Hasegawa et al., 2008). Here, CCR6 is linked to graft versus host disease.