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.

中文翻译：

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微米级氧化铁颗粒（MPIO）的抗体介导的外周T细胞细胞标记可通过MRI检测单个细胞。

用氧化铁标记细胞是基于MRI的细胞成像的有用工具。在此证明，可以用链霉亲和素涂层的微米级氧化铁颗粒（MPIO）在体外全血中标记外周大鼠T细胞，使铁浓度达到每个细胞60 pg铁。这是超细氧化铁（USPIO）报道的标记量的30倍。标记是通过使用生物素化的抗CD5抗体介导的，该抗体对周围T细胞具有特异性。这种标记允许使用非常适合于体内动物工作的条件通过MRI在体外检测单个淋巴细胞。电子显微镜分析表明，MPIOs在标记后仍大部分保留在细胞外，并有一些细胞内摄取的证据。细胞活力以及早期和晚期细胞因子释放研究表明标记和未标记细胞之间无显着差异。因此，使用MPIO来实现细胞MRI的高铁浓度可能是淋巴细胞非侵入性成像的一种有效的新形式。