Lu L, McCaslin D, Starzl T E, Thomson A W
Pittsburgh Transplantation Institute, University of Pittsburgh, Pennsylvania 15213, USA.
Transplantation. 1995 Dec 27;60(12):1539-45. doi: 10.1097/00007890-199560120-00028.
The functional maturation of dendritic cells (DC) and other antigen-presenting cells is believed to reflect the upregulation of cell surface major histocompatibility complex (MHC) class II and other T cell co-stimulatory molecules, especially the CD28 ligands B7-1 (CD80) and B7-2 (CD86). In this study, we propagated cells exhibiting characteristics of DC precursors from the bone marrow (BM) of B10 mice (H-2b; I-A+) in response to granulocyte-macrophage colony stimulating factor (GM-CSF). The methods used were similar to those employed previously to propagate DC progenitors from normal mouse liver. Cells expressing DC lineage markers (NLDC 145+, 33D1+, N418+) harvested from 8-10-day GM-CSF stimulated BM cell cultures were CD45+, heat-stable antigen+, CD54+, CD44+, MHC class II+, B7-1dim but B7-2- (costimulatory molecule-deficient). Supplementation of cultures with interleukin-4 (IL-4) in addition to GM-CSF however, resulted in marked upregulation of MHC class II and B7-2 expression. These latter cells exhibited potent allostimulatory activity in primary mixed leukocyte cultures. In contrast, the cells stimulated with GM-CSF alone were relatively weak stimulators and induced alloantigen-specific hyporesponsiveness in allogeneic T cells (C3H; H-2k; I-E+) detected upon restimulation in secondary MLR. This was associated with blockade of IL-2 production. Reactivity to third-party stimulators was intact. The hyporesponsiveness induced by the GM-CSF stimulated, costimulatory molecule-deficient cells was prevented by incorporation of anti-CD28 monoclonal antibody in the primary MLR and was reversed by addition of IL-2 to restimulated T cells. The findings show that MHC class II+ B7-2- cells with a DC precursor phenotype can induce alloantigen-specific hyporesponsiveness in vitro. Under the appropriate conditions, such costimulatory molecule-deficient cells could contribute to the induction of donor-specific unresponsiveness in vivo.
树突状细胞（DC）和其他抗原呈递细胞的功能成熟被认为反映了细胞表面主要组织相容性复合体（MHC）II类分子和其他T细胞共刺激分子的上调，尤其是CD28配体B7-1（CD80）和B7-2（CD86）。在本研究中，我们响应粒细胞-巨噬细胞集落刺激因子（GM-CSF），从B10小鼠（H-2b；I-A+）的骨髓（BM）中培养出具有DC前体特征的细胞。所使用的方法与先前用于从正常小鼠肝脏培养DC祖细胞的方法相似。从8-10天GM-CSF刺激的BM细胞培养物中收获的表达DC谱系标记（NLDC 145+、33D1+、N418+）的细胞为CD45+、热稳定抗原+、CD54+、CD44+、MHC II类+、B7-1低表达但B7-2阴性（共刺激分子缺陷）。然而，除GM-CSF外，在培养物中添加白细胞介素-4（IL-4）可导致MHC II类分子和B7-2表达显著上调。这些细胞在初次混合淋巴细胞培养中表现出强大的同种异体刺激活性。相比之下，仅用GM-CSF刺激的细胞是相对较弱的刺激物，并在二次混合淋巴细胞反应（MLR）再刺激时检测到的同种异体T细胞（C3H；H-2k；I-E+）中诱导同种异体抗原特异性低反应性。这与IL-2产生的阻断有关。对第三方刺激物的反应性未受影响。GM-CSF刺激的、共刺激分子缺陷的细胞诱导的低反应性可通过在初次MLR中加入抗CD28单克隆抗体来预防，并通过向再刺激的T细胞中添加IL-2来逆转。这些发现表明，具有DC前体表型的MHC II类+B7-2阴性细胞可在体外诱导同种异体抗原特异性低反应性。在适当条件下, 这种共刺激分子缺陷的细胞可能有助于在体内诱导供体特异性无反应性。
