CD34 and neoplasm: A number of strategies have therefore been taken to establish a human immune system in immunodeficient rodents to generate humanised PDX models: implantation of peripheral blood mononuclear cells, containing T cells, B cells, natural killer cells and monocytes, alongside the tumours25; implantation of fresh tumour containing human stromal and immune cells26; implantation of tumours into mice into which human CD34+ haematopoietic stem cells have previously been transplanted following sublethal irradiation27 to replace the full haematopoietic system, including innate and adaptive immunity.