Poon Grace F T, Dong Yifei, Marshall Kelsey C, Arif Arif, Deeg Christoph M, Dosanjh Manisha, Johnson Pauline
Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
J Immunol. 2015 Jul 15;195(2):632-42. doi: 10.4049/jimmunol.1402506. Epub 2015 Jun 17.
Although classical dendritic cells (DCs) arise from distinct progenitors in the bone marrow, the origin of inflammatory DCs and the distinction between monocyte-derived DCs and macrophages is less clear. In vitro culture of mouse bone marrow cells with GM-CSF is a well-established method to generate DCs, but GM-CSF has also been used to generate bone marrow-derived macrophages. In this article, we identify a distinct subpopulation of cells within the GM-CSF bone marrow-derived DC culture based on their ability to bind hyaluronan (HA), a major component of the extracellular matrix and ligand for CD44. HA identified a morphologically distinct subpopulation of cells within the immature DC population (CD11c(+) MHC II(mid/low)) that were CCR5(+)/CCR7(-) and proliferated in response to GM-CSF, but, unlike immature DCs, did not develop into mature DCs expressing CCR7 and high levels of MHC II, even after stimulation with LPS. The majority of these cells produced TNF-α in response to LPS but were unable to activate naive T cells, whereas the majority of mature DCs produced IL-12 and activated naive T cells. This HA binding population shared many characteristics with alveolar macrophages and was retained in the alveolar space after lung instillation even after LPS stimulation, whereas the MHC II(high) mature DCs were found in the draining lymph node. Thus, HA binding in combination with MHC II expression can be used to identify alveolar-like macrophages from GM-CSF-treated bone marrow cultures, which provides a useful in vitro model to study alveolar macrophages.
尽管经典树突状细胞（DCs）起源于骨髓中的不同祖细胞，但炎性DCs的起源以及单核细胞来源的DCs与巨噬细胞之间的区别尚不清楚。用GM-CSF体外培养小鼠骨髓细胞是一种成熟的生成DCs的方法，但GM-CSF也被用于生成骨髓来源的巨噬细胞。在本文中，我们基于细胞结合透明质酸（HA）的能力，在GM-CSF骨髓来源的DC培养物中鉴定出一个独特的细胞亚群，HA是细胞外基质的主要成分和CD44的配体。HA在未成熟DC群体（CD11c(+) MHC II（中/低））中鉴定出一个形态上不同的细胞亚群，这些细胞CCR5(+)/CCR7(-)，对GM-CSF有增殖反应，但与未成熟DCs不同，即使在用LPS刺激后，也不会发育成表达CCR7和高水平MHC II的成熟DCs。这些细胞中的大多数在受到LPS刺激后产生TNF-α，但无法激活初始T细胞，而大多数成熟DCs产生IL-12并激活初始T细胞。这个HA结合群体与肺泡巨噬细胞有许多共同特征，即使在LPS刺激后，经肺内灌注后仍保留在肺泡空间中，而MHC II（高）成熟DCs则在引流淋巴结中被发现。因此，HA结合与MHC II表达相结合可用于从GM-CSF处理的骨髓培养物中鉴定肺泡样巨噬细胞，这为研究肺泡巨噬细胞提供了一个有用的体外模型。
