BACKGROUND Contaminating breast cancer cells in leukapheresis harvested for reinfusion to rebuild hemopoiesis after high-dose therapy have been described by several investigators. Methods for tumor cell detection are conventional immunocytochemistry, culture techniques and reverse transcriptase PCR. The percentage of tumor cell positive leukaphereses shows a wide variation. An approach to clarify if these cells can induce systemic relapse is to characterize them molecular-genetically and immunologically, but these techniques require a sufficient cell count. METHODS We compared conventional immunocytochemistry with immunocytochemistry after immunomagnetic enrichment of cancer cells by HEA-125 magnetic microbeads for the detection of micrometastatic tumor cells. A total of 25 samples, consisting of 16 samples from G-CSF-mobilized peripheral stem cell harvests, eight BM aspirations and one peripheral blood sample were investigated without [median 2, range 1-3 x 10(6) MNCs] and after [median 5, range 1-10 x 10(7) MNCs] HEA-microbead selection. Additionally 10 buffy coat samples from healthy subjects were investigated. RESULTS Using conventional immunocytochemistry, tumor cells could be detected in nine stem cell samples. Two BM samples and the blood sample (48%) were positive, with a median tumor cell load of 0 (0-12) cells per sample (mean: 2.4). By HEA-bead selection the rate of positivity could be increased to 88% (13 stem cell samples, eight marrow samples and one blood sample) with a median load of 6 (0-47) (mean 10.6) suspected cells (p < 0.007). However, calculation of recovery revealed tumor cell losses by immunobead selection. False positive results were not seen. DISCUSSION We conclude first that immunomagnetic selection is an excellent and highly sensitive tool to enrich contaminating cancer cells from marrow and stem cell samples; second that the existence of real tumor cell negative stem cell harvests is doubtful; and third that immunobead selection delivers sufficient tumor cell counts for their further characterization by molecular and immunological methods.

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免疫磁性富集对乳腺癌细胞检测的改进

背景 一些研究人员已经描述了在白细胞去除术中收集的污染乳腺癌细胞用于再输注以在高剂量治疗后重建造血。检测肿瘤细胞的方法是常规的免疫细胞化学、培养技术和逆转录酶 PCR。肿瘤细胞阳性白细胞去除术的百分比显示出很大的变化。澄清这些细胞是否可以诱导全身复发的一种方法是从分子遗传学和免疫学上表征它们，但这些技术需要足够的细胞计数。方法 我们比较了常规免疫细胞化学与免疫细胞化学在通过 HEA-125 磁微珠对癌细胞进行免疫磁性富集后检测微转移肿瘤细胞的方法。共25个样本，由来自 G-CSF 动员的外周干细胞收获的 16 个样本、8 个 BM 抽吸和一个外周血样本组成，在没有 [中位数 2，范围 1-3 x 10(6) 个 MNC] 和 [中位数 5，范围 1- 10 x 10(7) MNCs] HEA-微珠选择。另外研究了来自健康受试者的 10 个血沉棕黄层样品。结果 使用常规免疫细胞化学，可以在九个干细胞样本中检测到肿瘤细胞。两个 BM 样本和血液样本 (48%) 呈阳性，每个样本的中位肿瘤细胞负载为 0 (0-12) 个细胞（平均值：2.4）。通过 HEA-bead 选择，阳性率可以增加到 88%（13 个干细胞样本、8 个骨髓样本和 1 个血液样本），中位负荷为 6 (0-47)（平均 10.6）个可疑细胞（p < 0.007 ）。然而，恢复的计算揭示了免疫珠选择导致的肿瘤细胞损失。没有看到假阳性结果。讨论 我们首先得出结论，免疫磁性选择是一种极好的和高度敏感的工具，可以从骨髓和干细胞样本中富集污染的癌细胞。第二，真正的肿瘤细胞阴性干细胞收获的存在值得怀疑；第三，免疫珠选择提供足够的肿瘤细胞计数，以便通过分子和免疫学方法进一步表征。