Purification of Peripheral Blood Natural Killer Cells

The ability to perform biological studies on natural killer (NK) cells requires effective methods for their isolation from hematopoietic cells of other lineages. NK cells are a discrete lymphocyte subset distinct from B and T cells based on both physical and phenotypic characteristics that can be exploited for their purification. Techniques based on differential cell buoyancy [centrifugation on discontinuous density gradients such as Percoll (1 )] have been used to enrich NK cells from mixed lymphocyte populations but do not allow their purification to homogeneity. The mononuclear cell suspensions obtained, although enriched in NK cells, also contain variable proportions of other cell types (monocytes and/or activated T and B cells) (2 ), and subsets of NK cells of higher density are lost in these preparations.