Natural Killer cells, also as known as NK cells, are a type of cytotoxic lymphocyte belong to the innate immune system which are important to adaptive immune response in vertebrate. Around 5-20% of all circulating lymphocytes are NK cells in human. Human NK Cell Isolation kit is designed to isolate untouched NK cells which contains a biotin labeled antibody cocktail and streptavidin conjugated magnetic beads. Through incubation of samples with biotin antibody cocktail followed by incubation of streptavidin beads, the magnetically labeled non-NK cells will be retained in the tube by magnetic separator. The untouched NK cells are collected in supernatant. Any downstream application can be performed on NK cells after separation, such as Flow Cytometry and in vitro culture.