Croockewit A J, Raymakers R A, Preijers F W, Vierwinden G, de Witte T J
Department of Medicine, University Hospital Nijmegen, The Netherlands.
Scand J Immunol. 1998 Jan;47(1):82-90. doi: 10.1046/j.1365-3083.1998.00261.x.
Positive selection of CD34+ cells is an attractive approach to reduce tumour cell contamination in bone marrow (BM) and peripheral blood progenitor cell (PBPC) autografts in malignancies not expressing CD34. All current selection methods use monoclonal antibodies (MoAbs) specific for the class I or class II CD34 epitopes, while for detection most investigators use class III MoAbs. Since the distribution of the different CD34 epitopes on haematopoietic progenitors differs, we studied their significance in CD34+ selection procedures. Testing MoAbs against class I, II and III CD34 epitopes on normal BM we observed that +/- 23% of class III positive cells was class I negative. A higher expression of the class III epitope compared with classes I or II was observed on the KG1 cell line, whereas no differences in binding capability were found. The class III epitope anti-CD34, 561, was compared with the class I epitope anti-CD34, BI-3C5, both coupled to M450 Dynabeads. The yield of CD34+ cells obtained with the 561 beads was 1.7% of the mononuclear cells versus 0.95% using the class I epitope, a 1.95-fold increase (1.3-2.7), whereas the purity was similar (96% in both cases). The absolute number of CD34+ cells was therefore twofold higher after 561 selection, including cells with a more mature phenotype. In single cell assay comparable numbers of highly proliferative progenitors but higher numbers of differentiated colonies per phenotypic subfraction were measured. In conclusion, M450 beads coated with the 561 anti-class III CD34 epitope are more efficient in isolating CD34+ cells from bone marrow, probably due to a broader distribution of the class III epitope.
对于不表达CD34的恶性肿瘤患者，通过阳性选择CD34+细胞来减少骨髓（BM）和外周血祖细胞（PBPC）自体移植物中的肿瘤细胞污染是一种有吸引力的方法。目前所有的选择方法都使用针对I类或II类CD34表位的单克隆抗体（MoAb），而在检测时大多数研究者使用III类MoAb。由于造血祖细胞上不同CD34表位的分布不同，我们研究了它们在CD34+选择程序中的意义。在用针对正常BM中I类、II类和III类CD34表位的MoAb进行检测时，我们观察到III类阳性细胞中有±23%为I类阴性。在KG1细胞系上观察到III类表位的表达高于I类或II类，而在结合能力上未发现差异。将与M450磁珠偶联的III类表位抗CD34、561与I类表位抗CD34、BI-3C5进行了比较。用561磁珠获得的CD34+细胞产量为单核细胞的1.7%，而使用I类表位时为0.95%，增加了1.95倍（1.3 - 2.7），而纯度相似（两种情况下均为96%）。因此，经561选择后CD34+细胞的绝对数量高出两倍，包括具有更成熟表型的细胞。在单细胞试验中，每个表型亚组分中可测量到相当数量的高增殖祖细胞，但分化集落的数量更多。总之，包被有561抗III类CD34表位的M450磁珠在从骨髓中分离CD34+细胞方面效率更高，这可能是由于III类表位的分布更广泛。
