title: Antibody-mediated cell labeling of peripheral T cells with micron-sized iron oxide particles (MPIOs) allows single cell detection by MRI.
abstract: Labeling cells with iron oxide is a useful tool for MRI based cellular imaging. Here it is demonstrated that peripheral rat T cells can be labeled in whole blood, in vitro, with streptavidin-coated micron-sized iron oxide particles (MPIOs), achieving iron concentrations as high as 60 pg iron per cell. This is 30 times the amount of labeling reported with ultrasmall particles of iron oxide (USPIOs). Labeling was mediated by use of a biotinylated anti-CD5 antibody, which is specific for peripheral T cells. Such labeling allowed the in vitro detection of single lymphocytes by MRI, using conditions well suited for in vivo animal work. Electron microscopic analysis demonstrated that MPIOs remained largely extracellular after labeling, with some evidence of intracellular uptake. Cell viability and early and late cytokine release studies showed no significant differences between labeled and unlabeled cells. Therefore, the use of MPIOs for achieving high iron concentrations for cellular MRI is potentially an effective new modality for non-invasive imaging of lymphocytes.
authors.affiliation: Molecular and Cellular Imaging Laboratory, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT, USA. erik.shapiro@yale.edu
authors.forename: Erik M
authors.initials: EM
authors.lastname: Shapiro
authors.forename: Laura N
authors.initials: LN
authors.lastname: Medford-Davis
authors.forename: Tarek M
authors.initials: TM
authors.lastname: Fahmy
authors.forename: Cynthia E
authors.initials: CE
authors.lastname: Dunbar
authors.forename: Alan P
authors.initials: AP
authors.lastname: Koretsky
mesh_terms: D000818:Animals; D000906:Antibodies / Q000737:chemistry*; D018956:CD5 Antigens / Q000737:chemistry; D002470:Cell Survival; D003287:Contrast Media / Q000494:pharmacology*; D016207:Cytokines / Q000378:metabolism; D005290:Ferric Compounds / Q000494:pharmacology*; D005434:Flow Cytometry; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008854:Microscopy, Electron; D008954:Models, Biological; D010316:Particle Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology*
chemical_list: D000906:Antibodies; D018956:CD5 Antigens; D003287:Contrast Media; D016207:Cytokines; D005290:Ferric Compounds; C000499:ferric oxide