A major step forward in the development of murine models of intestinal inflammation came with the discovery that adoptive transfer of naïve CD4+ T cells (CD4+CD45RBhigh T cells) from donor mice into syngeneic immunodeficient SCID or Rag1−/− recipient mice causes a wasting disease and a primarily colonic inflammation (Kiesler et al. 2015). The gene discussed is CD4; the disease is inflammation.