Gaipa Giuseppe, Coustan-Smith Elaine, Todisco Elisabetta, Maglia Oscar, Biondi Andrea, Campana Dario
Centro Ricerca M. Tettamanti, Clinica Pediatrica, Università Milano-Bicocca, Ospedale San Gerardo, via Donizetti 106, 20052 Monza (MI), Italy.
Haematologica. 2002 Apr;87(4):347-56.
Hematopoietic progenitor cells that express CD34 are heterogeneous in their lineage affiliation and degree of maturation. Expression of CD13 and CD33 antigens indicates myeloid lineage association, but the precise sequence of expression of these two markers during differentiation is unclear. We noted the presence of CD34+ cells expressing CD13 but lacking CD33, a subset of cells not yet well characterized. In this report we describe the prevalence and the immunophenotype of this cell subset.
We studied the immunophenotype of immature myeloid cells in human bone marrow samples from 11 healthy transplantation donors and in 4 cord blood samples. We used four-color flow cytometry and a large panel of monoclonal antibodies directed against lineage and differentiation-associated antigens. Three additional bone marrow samples were analyzed after immunomagnetic sorting of CD34+ cells. We focused our analysis on the subset of cells defined by the expression of CD34 and CD13 and the lack of CD33.
We found CD34+, CD13+, CD33- cells in all 11 bone marrow and 4 cord blood samples studied. These cells represented 0.5 0.5% (mean SD) and 0.8 1.2% of mononucleated cells, respectively. CD34+, CD13+, CD33- cells appeared to be more immature than those expressing CD33 because of their light scatter characteristics (smaller size and lower granularity), the expression of markers associated with early hematopoietic cells (CD90, CD133 and CD117), and the absence of lineage-associated markers.
These findings suggest that the expression of CD13 precedes that of CD33 during myeloid differentiation, and that CD34+, CD13+, CD33- cells are at an early stage of human myeloid cell differentiation.
表达CD34的造血祖细胞在谱系归属和成熟程度上具有异质性。CD13和CD33抗原的表达表明与髓系谱系相关，但这两种标志物在分化过程中的精确表达顺序尚不清楚。我们注意到存在表达CD13但缺乏CD33的CD34+细胞，这是一个尚未得到充分表征的细胞亚群。在本报告中，我们描述了该细胞亚群的发生率和免疫表型。
我们研究了来自11名健康移植供体的人骨髓样本和4份脐血样本中未成熟髓系细胞的免疫表型。我们使用四色流式细胞术和一大组针对谱系和分化相关抗原的单克隆抗体。在对CD34+细胞进行免疫磁珠分选后，对另外3份骨髓样本进行了分析。我们的分析集中在由CD34和CD13的表达以及CD33的缺乏所定义的细胞亚群上。
在所有研究的11份骨髓和4份脐血样本中均发现了CD34+、CD13+、CD33-细胞。这些细胞分别占单核细胞的0.5±0.5%（均值±标准差）和0.8±1.2%。由于其光散射特征（较小的尺寸和较低的颗粒度）、与早期造血细胞相关的标志物（CD90、CD133和CD117）的表达以及缺乏谱系相关标志物，CD34+、CD13+、CD33-细胞似乎比表达CD33的细胞更不成熟。
这些发现表明在髓系分化过程中CD13的表达先于CD33，并且CD34+、CD13+、CD33-细胞处于人类髓系细胞分化的早期阶段。
