Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Antitumor response of CD14(+)/CD16(+) monocyte subpopulation

Abstract

OBJECTIVE: Two main subpopulations of human blood monocytes are distinguished on the basis of CD14 and CD16 expression: the major population with enhanced expression of CD14 (CD14(++) monocytes) and the minor one with a weak expression of CD14 coexpressing CD16 (CD14(+)/CD16(+) monocytes). As monocytes and macrophages are involved in antitumor response of the host, we assessed the ability of CD14(+)/CD16(+) monocytes to produce cytokines (intracellular expression, release) and reactive oxygen and nitrogen (ROI, RNI) intermediates following stimulation in vitro with tumor cells. MATERIALS AND METHODS: Monocytes were isolated by elutriation and their subpopulations by FACS sorting. Monocytes and their subpopulations were cocultured with tumor cells. Cytokine (TNF-alpha, IL-12, and IL-10) production was assessed by determination of intracellular protein expression by flow cytometry, and release by ELISA. ROI induction was detected by chemiluminescence and O(2)(-) production by flow cytometry, whereas RNI by intracellular expression of inducible NO synthase (iNOS) and nitric oxide (NO) release assessed colorimetrically. RESULTS: CD14(+)/CD16(+) monocytes stimulated with tumor cells showed significantly enhanced production of TNF-alpha, IL-12p40, IL-12p70 (intracellular expression, release), whereas little IL-10 release was observed. CD14(+)/CD16(+) subpopulation did not produce ROI, but showed an increased iNOS expression and NO release. CD14(+)/CD16(+) monocytes also exhibited enhanced cytotoxic and cytostatic activities against tumor cells. CONCLUSIONS: CD14(+)/CD16(+) cells constitute the main subpopulation of blood monocytes involved in antitumor response as judged by enhanced production of proinflammatory cytokines, RNI, and increased cytotoxic/cytostatic activity.