CD16CD56

CD16CD56 refers to cells that express both CD16 (Fc gamma receptor III) and CD56 (neural cell adhesion molecule), a combination commonly used to identify human natural killer (NK) cells by flow cytometry. CD16 is the receptor that mediates antibody-dependent cellular cytotoxicity, while CD56 is associated with NK cell development and adhesion. Together, these markers help distinguish NK cell subsets and separate NK cells from other lymphocytes in immunophenotyping.

In peripheral blood, NK cells are traditionally divided into two major subsets based on CD56 and CD16 expression: CD56bright CD16- NK cells, which are less cytotoxic but produce cytokines, and CD56dim CD16+ NK cells, which are highly cytotoxic and comprise the majority of circulating NK cells. A subset expressing both CD56 and CD16 (CD56+CD16+) is also observed, often interpreted as an activated or transitional NK cell population, with frequencies varying by age, infection, or inflammation. Less common NK cell populations can be CD56-, CD16-, or CD56dim CD16-, depending on context and tissue.

Functionally, CD16 enables NK cells to kill antibody-coated targets through ADCC, while CD56 is involved in cell adhesion, tissue localization, and interactions with other immune cells. Activation, maturation, or disease states can shift the expression balance of these markers, influencing NK cell behavior.

Clinical and research relevance: CD56 and CD16 are standard markers in immunophenotyping to characterize NK cell populations and distinguish them from T cells (often gated as CD3- CD56+). Aberrant patterns can appear in NK cell disorders or malignancies; for example, extranodal NK/T-cell lymphoma often shows CD56 expression. Marker profiles may also change during infection or inflammatory conditions, highlighting the utility and limitations of CD16CD56-based identification.