CD34 and graft versus host disease: These models represent a valuable tool for the preclinical evaluation of immunotherapies.<h4>Methods</h4>In this study, we provide a comprehensive comparison of two widely used HIS models: the Hu-CD34+ model, which engrafts Hu-hematopoietic cells derived from Hu-CD34+ hematopoietic stem cells (HSCs), and the Hu-PBMC model, which utilizes Hu-peripheral blood mononuclear cells (PBMCs).<h4>Results</h4>We assess the kinetics, quality and extent of immune cell engraftment, as well as the development of graft-versus-host disease (GVHD).