Chapter Nine - Isolation, culture and propagation of natural killer cells

Abstract

Natural killer (NK) cells are essential effector cells of the innate immune system, which rapidly recognize and directly destroy virally infected and transformed cells, mediate inflammation, and regulate innate and adaptive immune function via interaction with other immune cells such as spontaneous killing of infected and transformed cells, inflammation, engraftment of hematopoetic stem cells and regulation of immune function. NK cells have been used to treat viral infections and malignancies as well as to increase engraftment of bone marrow stem cell transplants in experimental animal models and humans. NK cells represent one of the first lines of host immune defense against viruses and cancer as well as central regulators of immune function. NK cells represent a relatively small population of cells that is mixed with other populations of immune cells within the immune system. In order to study or utilize NK cells in therapy, they are often isolated from other immune cells. Based on their specific buoyant, phenotypic and functional characteristics, several effective ex vivo techniques for isolation and expansion of NK cells have been developed and successfully utilized. The most frequently used techniques for isolation and expansion of NK cells are presented and detailed protocols for purification of NK cells using magnet activated cell sorting (MACS) and separation and expansion of IL-2-activated adherent NK (A-NK) cells are provided. The most frequently used techniques include Percoll density gradient centrifugation, panning, sheep red blood cell rosetting, fluorescence activated cell sorting, magnet activated cell sorting, and IL-2-induced cell adherence selection.