CD28 and graft versus host disease: While many publications have utilized Pan T-cell activators (e.g., PHA or anti-CD3/anti-CD28) to model T-cell-mediated pathologies (e.g., allorecognition, transplant rejection, GvHD, autoimmunity and inflammation) (Maciel et al. 1976; Trickett and Kwan 2003), our results clearly indicate that there are very significant differences in the miRNA response pattern of human PBMC at 72 h (well into the proliferation and differentiation cycle) between the activation strategies (Fig. 5).