Center of Allergy and Environment (ZAUM), Technische Universität München and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany.
Christine Kühne - Center for Allergy Research and Education, CK-CARE, Davos, Switzerland.
Allergy. 2015 Nov;70(11):1450-60. doi: 10.1111/all.12707. Epub 2015 Aug 28.
B cells play a central role in IgE-mediated allergies. In damaged airway epithelium, they are exposed directly to aeroallergens. We aimed to assess whether direct exposure of B cells to pollen constituents affects allergic sensitization.
B cells from murine splenocytes and from blood samples of healthy donors were incubated for 8 days under Th2-like conditions with aqueous ragweed pollen extracts (Amb-APE) or its constituents. Secreted total IgM, IgG, and IgE was quantified by ELISA. Additionally, birch, grass, or pine-pollen extracts were tested. The number of viable cells was evaluated by ATP measurements. B-cell proliferation was measured by CFSE staining. IgE class switch was analyzed by quantitation of class switch transcripts. In an OVA/Alum i.p.-sensitization mouse model, Amb-APE was intranasally instilled for 11 consecutive days.
Upon Th2 priming of murine B cells, ragweed pollen extract caused a dose-dependent increase in IgE production, while IgG and IgM were not affected. The low-molecular-weight fraction and phytoprostane E1 (PPE1) increased IgE production, while Amb a 1 did not. PPE1 enhanced IgE also in human memory B cells. Under Th1 conditions, Amb-APE did not influence immunoglobulin secretion. The IgE elevation was not ragweed specific. It correlated with proliferation of viable B cells, but not with IgE class switch. In vivo, Amb-APE increased total IgE and showed adjuvant activity in allergic airway inflammation.
Aqueous pollen extracts, the protein-free fraction of Amb-APE, and the pollen-contained substance PPE1 specifically enhance IgE production in Th2-primed B cells. Thus, pollen-derived nonallergenic substances might be responsible for B-cell-dependent aggravation of IgE-mediated allergies.
B 细胞在 IgE 介导的过敏反应中发挥核心作用。在受损的气道上皮中，它们直接暴露于气传过敏原中。我们旨在评估 B 细胞直接暴露于花粉成分是否会影响过敏致敏。
在 Th2 样条件下，用Amb-APE（豚草花粉提取物）或其成分孵育来自鼠脾细胞和健康供体血液的 B 细胞 8 天。通过 ELISA 定量测定分泌的总 IgM、IgG 和 IgE。此外，还测试了桦树、草或松树花粉提取物。通过 ATP 测量评估活细胞数。通过 CFSE 染色测量 B 细胞增殖。通过定量分析类别转换转录本分析 IgE 类别转换。在 OVA/Alum 腹腔内致敏小鼠模型中，连续 11 天用 Amb-APE 滴鼻给药。
在 Th2 致敏鼠 B 细胞后，豚草花粉提取物引起 IgE 产生的剂量依赖性增加，而 IgG 和 IgM 不受影响。低分子量部分和植物前列腺素 E1（PPE1）增加 IgE 产生，而 Amb a 1 则没有。PPE1 还增强了人记忆 B 细胞中的 IgE。在 Th1 条件下，Amb-APE 不影响免疫球蛋白分泌。IgE 升高不是豚草特异性的。它与存活 B 细胞的增殖相关，但与 IgE 类别转换无关。在体内，Amb-APE 增加了总 IgE，并在变应性气道炎症中显示出佐剂活性。
水性花粉提取物、Amb-APE 的无蛋白部分和花粉含有的物质 PPE1 特异性增强 Th2 致敏 B 细胞中的 IgE 产生。因此，花粉衍生的非过敏原物质可能是导致 B 细胞依赖性 IgE 介导过敏加重的原因。
