The CD16 Flow Cytometry test is a laboratory procedure used to identify and quantify Natural Killer (NK) cells in blood or bone marrow. NK cells are a type of lymphocyte critical for innate immunity, responsible for destroying virus-infected and malignant cells.

The test uses fluorescently labeled antibodies against CD16 (FcγRIII receptor), which is expressed on NK cells, to detect and measure these cells in a sample. By combining CD16 staining with other markers (commonly CD56 and CD3), the test can differentiate NK cell subpopulations and assess immune status.