In line with these studies, Xystrakis et al. (2004a) have employed a parent-into-F1 HCT model and showed that CD4+ CD45RClo T cells containing mainly memory T cells, in contrast to CD4+ CD45RChi T cells containing mainly naive T cells, failed to induce acute or chronic GvHD in recipient rats. Here, CD4 is linked to graft versus host disease.