Natural killer cells were first described in 1975. These feisty little cells have the ability to spontaneously recognize and kill cancerous cells - which is how they got their name. In 1992, whilst studying transplantation of bone marrow cells in leukemia patients, Jeff described how natural killer cells found in the blood matured from a population of stem cells found in the bone marrow. In 2005, Jeff led a study describing the first infusion of natural killer cells derived from a donor's blood to a patient to help treat their leukemia. In 2014, we described how suppressive cells, known as regulatory T cells, can hinder these therapeutic natural killer cells. In 2017, demonstrating how safe natural killer activation is as a therapy - the first patient was treated as an outpatient with a cytokine to activate natural killer cells. 2019 saw the first natural killer cell infusion to treat HIV. In search of a more scalable source of natural killer cells, Jeff began a collaboration with industry partners, Fate Therapeutics, who manufacture natural killer cells from skin cells reprogrammed into stem cells. 2019 saw the first multi-dose infusion of these re-programmed natural killer cells, whilst 2020 saw our first trial of the biologic 'tri-specific killer engagers' that help a patient's own natural killer cells to find cancerous cells and destroy them.