CD24 and graft versus host disease: Targeted mutations of either CD24 or Siglecg in the hematopoietic cells greatly exacerbated GVHD, while treatment with CD24Fc, a fusion protein consisting of extracellular domain of CD24 and IgG1 Fc, prevented the development of GvHD by targeting the Siglec G on the hematopoietic cells (13).