Natural killer (NK) cells are heterogeneous and are divided into CD56~(bright) and CD56~(dim) subsets according to surface CDS6 expression, where CD56~(dim) NK cells constitute approximately 90% of human peripheral blood NK cells and display high cytotoxicity ex vivo. Broadly speaking, 2 major classes of stimuli are responsible for NK-cell activation: target cell recognition and cytokine stimulation. Upon exogenous stimulation with proinflamma-tory cytokines such as interleukin-12 (IL-12), IL-1S, and IL-18, CD56~(bright) NK cells secrete a greater amount of cytokines (eg, interferon gamma [IFN-gamma] and tumor necrosis factor alpha [TNF-alpha]) relative to CD56~(dim) NK cells. The current study by Fauriat et al demonstrates that, in response to target cell recognition, CD56~(dim) NK cells rather than CD56~(bright) NK cells are primarily responsible for production of cytokines and chemokines (see figure).
展开▼
