Regulatory system of human mast cell production

我们试图用干细胞因子（SCF）从CD 34 ^+脐带血细胞中选择性产生的肥大细胞来阐明IL-6对人肥大细胞生长和特性的影响。向含有肥大细胞的培养物中加入IL-6导致SCF在液体培养物中生长的后代数量大幅减少。这种IL-6介导的肥大细胞生长抑制可能部分是由于在前体水平的抑制，根据克隆细胞培养测定的结果。此外，流式细胞术分析显示，在SCF+IL-6存在下生长的培养的肥大细胞具有降低的c-kit表达。与单独使用SCF获得的值相比，暴露于SCF+IL-6培养的肥大细胞也引起细胞大小、糜酶阳性细胞的频率和细胞内组胺水平的实质性增加。流式细胞术分析显示，在细胞表面低但显著水平的IL-6受体（IL-6 R）和gp 130表达。 ...更多信息 加入抗IL-6 R抗体或抗gp 130抗体可使IL-6的生物学功能消失。虽然IL-4和IL-6对SCF刺激下培养的肥大细胞的作用相似，但对比实验结果表明，这两种细胞因子使用不同的调节机制。综上所述，本研究结果表明，IL-6调节SCF依赖的人肥大细胞的发育直接通过IL-6 R-gp 130系统。以培养10周的CD 34 ^+脐血细胞来源的肥大细胞为靶细胞，全反式维甲酸（ATRA）和9-顺式维甲酸（9-cis RA）均以剂量依赖方式抑制SCF刺激下的子代生成。根据单个CD 34 ^+c-kit^+脐带血细胞培养研究，肥大细胞发育的早期阶段似乎对RA不太敏感。最佳浓度的RA还可降低肥大细胞中组胺的含量（SCF单独组为3.00±0.47 pg/cell，SCF+ATRA组为1.44±0.18 pg/cell，SCF+9-cis RA组为1.41±0.10 pg/cell）。RT-PCR分析显示，培养10周的肥大细胞中RARα、RARβ、RXRα和RXRβ mRNA均有表达。添加10 μ M至10 μ M的RAR选择性激动剂<-10><-7>可减少SCF中生长的肥大细胞数量，而高达10 μ M的RXR选择性激动剂<-8>则无活性。在10 μ M至10 μ M的RAR亚型选择性类维生素A中<-9><-7>，只有RARα激动剂<-7>在抑制肥大细胞生长的能力方面与10 μ M的ATRA相当。相反，加入过量浓度的RARα拮抗剂可显著抵消类维生素A介导的抑制作用。这些结果表明，RA抑制SCF依赖的人肥大细胞祖细胞的分化，通过一个特定的受体。少

We attempted to clarify the effects of IL-6 on the growth and properties of human mast cells using cultured mast cells selectively generated by stem cell factor (SCF) from CD34^+ cord blood cells. The addition of IL-6 to cultures containing mast cells resulted in a substantial reduction of the number of progenies grown by SCF in the liquid culture. This IL-6-mediated inhibition of mast cell growth may be due in part to the suppression at the precursor level, according to the results of a clonal cell culture assay. Moreover, a flow cytometric analysis showed that the cultured mast cells grown in the presence of SCF+IL-6 had decreased c-kit expression. The exposure of cultured mast cells to SCF+IL-6 also caused substantial increases in the cell size, frequency of chymase-positive cells and intracellular histamine level compared with the values obtained with SCF alone. The flow cytometric analysis revealed low but significant levels of expression of IL-6 receptor (IL-6R) and gp130 on the … More cultured mast cells grown with SCF.The addition of either anti-IL-6R antibody or anti-gp130 antibody abrogated the biological functions of IL-6. Although IL-4 exerted an effect similar to that of IL-6 on the cultured mast cells under stimulation with SCF, the results of comparative experiments suggest that the two cytokines use different regulatory mechanisms. Taken together, the present findings suggest that IL-6 modulates SCF-dependent human mast cell development directly via an IL-6R-gp130 system.Next, we examined the effects of retinoids on the human mast cell development using a serum-deprived culture system. When 10-week cultured mast cells derived from CD34^+ cord blood cells were used as target cells, both all-trans retinoic acid (ATRA) and 9-cis RA inhibited the progeny generation under stimulation with SCF in a dose-dependent manner. The early steps in mast cell development appear to be less sensitive to RA according to the single CD34^+c-kit^+ cord blood cell culture study. The optimal concentration of RAs also reduced the histamine concentration in the cultured mast cells (3.00±0.47 pg/cell in SCF alone, 1.44±0.18 pg/cell in SCF+ATRA, and 1.41±0.10 pg/cell in SCF+9-cis RA). RT-PCR analyses showed the expression of RARα, RARβ, RXRα and RXRβ mRNA in 10-week cultured mast cells. The addition of an RAR-selective agonist at 10^<-10> M to 10^<-7> M decreased the number of mast cells grown in SCF, whereas an RXR-selective agonist at up to 10^<-8> M was inactive. Among RAR subtype selective retinoids used at 10^<-9> M to 10^<-7> M, only the RARα agonist was equivalent to ATRA at 10^<-7> M in its ability to inhibit mast cell growth. Conversely, the addition of excess concentrations of a RARα antagonist profoundly counteracted the retinoid-mediated suppressive effects. These results suggest that RA inhibits SCF-dependent differentiation of human mast cell progenitors through a specific receptor. Less