Background

CD25⁺ human mast cells (huMCs) have been reported in patients with monoclonal mast cell diseases and in rare association with inflammation. However, the regulation of CD25 expression on huMCs and the possible biologic consequences remain poorly understood.

Objective

We sought to identify conditions that would upregulate CD25 expression on huMCs and to explore possible functional implications.

Methods

huMCs were cultured from peripheral blood progenitor cells over 6 to 8 weeks. Expression of CD25 was determined by fluorescence-activated cell sorting and soluble CD25 by ELISA. Signal transducer and activator of transcription 5 (STAT5) phosphorylation induced by IL-2 in huMCs, regulatory T (Treg) cells, or in cocultured huMCs and Treg cells was examined by fluorescence-activated cell sorting.

Results

Addition of IL-3 to CD34⁺ progenitors at the initiation of huMC cultures in the presence of stem cell factor and IL-6 upregulated the expression of CD25 in developing huMCs and resulted in shedding of soluble CD25 into the media. Removal of IL-3 after the first week of culture did not affect subsequent expression of CD25. Furthermore, addition of IL-3 14 days after the initiation of the culture did not induce significant CD25 expression. Treatment with anti–IL-3 antibody or the Janus kinase inhibitor tofacitinib blocked IL-3–induced CD25 upregulation. Binding of IL-2 to CD25⁺ huMCs did not induce STAT5 phosphorylation. However, coincubation of Treg cells with CD25⁺ huMCs pretreated with IL-2 was sufficient to result in STAT5 phosphorylation in Treg cells.

Conclusions

IL-3 promotes CD25 expression and shedding by huMCs. Although CD25⁺ huMCs do not respond to IL-2, they bind IL-2 and may act as a reservoir of IL-2 to then activate lymphocytes.

中文翻译：

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IL-3 上调 CD25 表达对人肥大细胞的证明和意义

背景

据报道， CD25 ⁺人肥大细胞 (huMC) 存在于患有单克隆肥大细胞疾病的患者中，并且很少与炎症相关。然而，对于 huMC 上 CD25 表达的调节和可能的生物学后果仍然知之甚少。

客观的

我们试图确定会上调 huMC 上的 CD25 表达的条件，并探索可能的功能影响。

方法

huMCs 在 6 到 8 周内从外周血祖细胞中培养出来。CD25 的表达通过荧光激活细胞分选法测定，可溶性 CD25 通过 ELISA 测定。通过荧光激活细胞分选检查 huMC、调节性 T (Treg) 细胞或共培养的 huMC 和 Treg 细胞中 IL-2 诱导的信号转导和转录激活因子 5 (STAT5) 磷酸化。

结果

在存在干细胞因子和 IL-6 的情况下，在 huMC 培养开始时向 CD34 + 祖细胞添加 IL-3 会上调发育中的 huMC 中 CD25 的表达，并导致可溶性 CD25 脱落到培养基中^。培养第一周后去除 IL-3 不影响随后的 CD25 表达。此外，在培养开始后 14 天添加 IL-3 不会诱导显着的 CD25 表达。用抗 IL-3 抗体或 Janus 激酶抑制剂托法替尼治疗可阻断 IL-3 诱导的 CD25 上调。^{IL-2 与 CD25 +} huMC 的结合不诱导 STAT5 磷酸化。^{然而，Treg 细胞与用 IL-2 预处理的 CD25 +} huMC共孵育足以导致 Treg 细胞中的 STAT5 磷酸化。

结论

IL-3 促进 huMC 的 CD25 表达和脱落。尽管 CD25 ⁺ huMC 对 IL-2 没有反应，但它们结合 IL-2 并可能充当 IL-2 的储库，然后激活淋巴细胞。