How can I analyze natural killer cells using flow cytometry?

Natural killer cells (NK cells) present various cell markers on the surface, including multiple clusters of differentiation (e.g. CD16, CD56, CD94), killer Immunoglobulin-like receptors (KIR), as well as natural cytotoxicity receptors (NCR). These markers are commonly used in flow cytometry to identify NK cells, where cells are stained with fluorochrome conjugated antibodies.

In humans, NK cells are typically defined as CD3^-CD56⁺ cells. Two different subtypes have been identified: CD3^-CD56^dimCD16⁺ and CD3^-CD56^brightCD16^-. In mice, NK cells are defined as CD3^-NK1.1⁺ cells. Three subsets are characterized based on the differential expression of Integrin alpha M/CD11b and CD27, including CD11^dimCD27^bright NK cells, CD11b^brightCD27^dim NK cells, and CD11b^brightCD27^bright NK cells.