Natural killer (NK) cells are an important part of the innate immune system and are responsible for killing virally infected cells by secreting cytotoxic granules. Activated NK cells also secrete a variety of cytokines that regulate the function of other cells in the immune system. NK cells are tightly regulated by stimulatory and inhibitory receptors that recognise cellular stress ligands and human leucocyte antigen class-I (HLA-1). A number of inhibitory and stimulatory receptors can be expressed in a stochastic and overlapping manner, sometimes resulting in over 30,000 NK cell phenotypes in a given individual.
This data sheet describes a flow-cytometry based immunophenotyping assay to define the major subsets of human NK cells and to characterise the key stimulatory and inhibitory receptors. The expression of key stimulatory and inhibitory receptors was first studied using two 12-color flow cytometry panels on the BD LSRFortessa™ analyser. This enabled the evaluation of a backbone panel of six NK cell lineage markers, combined with six either stimulatory or inhibitory markers. Combining these markers, an 18-color panel was designed to simultaneously assess all the markers in one tube. The 355-nm ultraviolet option on the BD LSRFortessa™ X-20 and the associated BD Horizon Brilliant ™ Ultraviolet reagents allowed the spreading of the 18 markers across an additional laser line. This allowed for more fluorochrome choice, less overlap, and maximizing marker information in one single tube.