CD56bright natural killer (NK) cells: an important NK cell subset

Abstract

Human natural killer (NK) cells can be subdivided into different populations based on the relative expression of the surface markers CD16 and CD56. The two major subsets are CD56(bright) CD16(dim/) (-) and CD56(dim) CD16(+), respectively. In this review, we will focus on the CD56(bright) NK cell subset. These cells are numerically in the minority in peripheral blood but constitute the majority of NK cells in secondary lymphoid tissues. They are abundant cytokine producers but are only weakly cytotoxic before activation. Recent data suggest that under certain conditions, they have immunoregulatory properties, and that they are probably immediate precursors of CD56(dim) NK cells. CD56(bright) NK cell percentages are expanded or reduced in a certain number of diseases, but the significance of these variations is not yet clear.

Figure 1

Natural killer (NK) cell subsets in human peripheral blood based on the relative expression of CD16 and CD56. Normal peripheral blood mononuclear cells (PBMC) were stained with anti-CD3, anti-CD14, anti-CD16, anti-CD19 and anti-CD56 antibodies conjugated to five different fluorochromes. A gate was set on CD3⁻ CD19⁻ cells (NK cells) and CD16 expression versus CD56 expression is shown. 1, CD56^bright CD16⁻; 2, CD56^bright CD16^dim; 3, CD56^dim CD16⁻; 4, CD56^dim CD16⁺; 5, CD56⁻ CD16⁺.