Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Different capacity of monocyte subsets to phagocytose iron-oxide nanoparticles.

Abstract

OBJECTIVE: To explore the capacity of human CD1Á�CD16Á�Á� and CD14Á�Á�CD16Á� monocytes to phagocyte iron-oxide nanoparticles in vitro. METHODS: Human monocytes were labeled with four different magnetic nanoparticle preparations (Ferumoxides, SHU 555C, CLIO-680, MION-48) exhibiting distinct properties and cellular uptake was quantitatively assessed by flow cytometry, fluorescence microscopy, atomic absorption spectrometry and Magnetic Resonance Imaging (MRI). Additionally we determined whether cellular uptake of the nanoparticles resulted in phenotypic changes of cell surface markers. RESULTS: Cellular uptake differed between the four nanoparticle preparations. However for each nanoparticle tested, CD14Á�Á�CD16Á� monocytes displayed a significantly higher uptake compared to CD14Á�CD16Á�Á� monocytes, this resulted in significantly lower T1 and T2 relaxation times of these cells. The uptake of iron-oxide nanoparticles further resulted in a remarkable shift of expression of cell surface proteins indicating that the labeling procedure affects the phenotype of CD14Á�CD16Á�Á� and CD14Á�Á�CD16Á� monocytes differently. CONCLUSION: Human monocyte subsets internalize different magnetic nanoparticle preparations differently, resulting in variable loading capacities, imaging phenotypes and likely biological properties.