Lamoureux Josée, Stankova Jana, Rola-Pleszczynski Marek
Immunology Division, Department of Pediatrics, Faculty of Medicine, Université de Sherbrooke, Quebec, Canada.
J Allergy Clin Immunol. 2006 Apr;117(4):924-30. doi: 10.1016/j.jaci.2005.12.1329. Epub 2006 Feb 7.
Cysteinyl-leukotrienes (cysLTs) are lipid mediators recognized for their role in asthma and allergic inflammation. CysLT1, one of the receptors for cysLTs, is expressed, among others, in bronchial smooth muscle cells, phagocytes, and B lymphocytes. The potential role of CysLT1 in B lymphocytes remains unexplored.
We examined the modulation of expression and function of CysLT1 in human B lymphocytes.
Human B lymphocytes were purified from peripheral blood and analyzed by means of RT-PCR and flow cytometry, after culture with IL-4 and anti-CD40 antibody or CD154-transfected fibroblasts. Functional responses to leukotriene (LT) D4 in terms of cytosolic calcium flux, proliferation, and immunoglobulin production were also examined.
B lymphocytes expressed CysLT1 at both the mRNA and protein levels. Two-fold to 3-fold enhancement of CysLT1 expression was observed after B-cell exposure to a combination of activating anti-CD40 antibody and IL-4. The expression of CysLT1 was also enhanced when B lymphocytes were cocultured with CD154-transfected fibroblasts in the presence of IL-4. Moreover, IL-4 and CD40-activated B lymphocytes showed an increased responsiveness to LTD4 in terms of cytosolic calcium flux, which was totally prevented by the selective CysLT1 antagonist montelukast. Stimulation of IL-4 and CD40-activated B lymphocytes with picomolar concentrations of LTD4 induced mature epsilon transcripts and upregulated IgE and IgG production 2-fold to 3-fold.
We have demonstrated that expression of CysLT1 can be upregulated in B lymphocytes after stimulation with CD154, with consequent increased responsiveness of the cells to LTD4 in terms of immunoglobulin production.
This study provides evidence that cysLTs generated during allergic reactions can affect B-cell function and enhance IgE and IgG production, which may further contribute to the allergic process.
半胱氨酰白三烯（cysLTs）是一类脂质介质，因其在哮喘和过敏性炎症中的作用而被人们所认识。CysLT1是cysLTs的受体之一，在支气管平滑肌细胞、吞噬细胞和B淋巴细胞等细胞中均有表达。CysLT1在B淋巴细胞中的潜在作用尚未得到充分研究。
我们研究了人B淋巴细胞中CysLT1表达和功能的调节。
从外周血中纯化人B淋巴细胞，在与白细胞介素-4（IL-4）和抗CD40抗体或CD154转染的成纤维细胞共培养后，通过逆转录聚合酶链反应（RT-PCR）和流式细胞术进行分析。还检测了白三烯（LT）D4在细胞内钙流、增殖和免疫球蛋白产生方面的功能反应。
B淋巴细胞在mRNA和蛋白质水平均表达CysLT1。在B细胞暴露于激活的抗CD40抗体和IL-4的组合后，观察到CysLT1表达增强了2至3倍。当B淋巴细胞在IL-4存在下与CD154转染的成纤维细胞共培养时，CysLT1的表达也增强。此外，IL-4和CD40激活的B淋巴细胞在细胞内钙流方面对LTD4的反应性增加，这被选择性CysLT1拮抗剂孟鲁司特完全阻断。用皮摩尔浓度的LTD4刺激IL-4和CD40激活的B淋巴细胞可诱导成熟的ε转录本，并使IgE和IgG产生上调2至3倍。
我们已经证明，在用CD154刺激后，B淋巴细胞中CysLT1的表达可以上调，从而使细胞在免疫球蛋白产生方面对LTD4的反应性增加。
本研究提供了证据，表明在过敏反应期间产生的cysLTs可以影响B细胞功能并增强IgE和IgG的产生，这可能进一步促进过敏过程。
