ABSTRACT
The majority of protocols which have been used for the generation of cloned cell lines displaying natural killer (NK)-like activity have been variants on a common theme, and can be considered as comprising three basic steps: the selection of a starting population, the placing of this population in culture medium containing appropriate growth factors, and the cloning of the culture. A basic assumption implicit in all attempts to generate NK cell clones is that NK cells themselves can proliferate. Some evidence to suggest that NK cells may divide in vivo has in fact been described by C. A. Biron et al. In the absence of any knowledge as to the growth factor requirements of NK cells, the pragmatic approach has been to use crude growth factor preparations, usually obtained as supernatants from lectin-stimulated spleen cells or blood mononuclear cells.
