Regulation of B cell function by the immunosuppressive agent leflunomide
Regulation of B cell function by the immunosuppressive agent leflunomide
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DOI：
10.1097/00007890-199602270-00020
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发表时间：
1996-02-27
期刊：
影响因子：
6.2
通讯作者：
Finnegan, A
中科院分区：
文献类型：
--
作者：
Siemasko, KF;Chong, ASF;Finnegan, A
来氟米特是一种免疫抑制药物，能够在体内抑制细胞和体液调节的反应。体内抑制B细胞抗体反应的机制尚未确定。在这项研究中，我们证明来氟米特通过直接作用于B细胞来抑制小鼠B细胞抗体的产生。体内实验表明，来氟米特既能抑制T细胞依赖的抗原反应，也能抑制T细胞非依赖的抗原反应。初步的体外实验表明，来氟米特通过抑制B细胞增殖而抑制B细胞抗体的产生。来氟米特对B细胞增殖的抑制作用表明，来氟米特作用于B细胞增殖所需的一个共同成分。对脂多糖激活的B细胞的动力学研究表明，来氟米特在刺激后24小时仍保持其抑制活性。通过对脂多糖刺激的B细胞周期的分析，我们观察到来氟米特作用于细胞周期的两个不同的阶段：(1)从G1期到S期；(2)从S期到G2/M期。Western印迹分析细胞周期蛋白依赖性蛋白CDK2的表达，发现来氟米特刺激48h后，CDK2的表达水平降低。这些数据进一步证实来氟米特通过S期抑制B细胞的生长。我们还提供了外源性尿苷逆转来氟米特抗增殖活性的证据。这表明来氟米特作为一种嘧啶合成抑制剂，从而抑制B细胞的增殖和细胞周期的进展。
Leflunomide is an immunosuppressive drug capable of inhibiting cellular and humoral mediated responses in vivo. The mechanism responsible for suppression of B cell antibody responses in vivo has not been identified. In this study we demonstrate that leflunomide functions to inhibit murine B cell antibody production by directly acting on the B cell. Experiments performed in vivo showed that both T cell-dependent as well as T cell-independent antigen responses were suppressed by leflunomide. Initial in vitro experiments demonstrated that leflunomide inhibited B cell antibody production by decreasing B cell proliferation. The suppression of B cell proliferation induced by a variety of stimuli that use different signal cascade components suggested that leflunomide was acting on a common component required for B cell proliferation, Kinetic studies with LPS activated B cells revealed that leflunomide retained its inhibitory activity when added as late as 24 hr after stimulation in an 88-hr assay, By analyzing the cell cycle of LPS-stimulated B cells we observed that leflunomide targets two different stages in cell cycle transition: (1) from G1 to S phase and (2) from S phase to G2/M phase. Analysis of one of the cyclin-dependent kinases, Cdk2 protein, by Western blot revealed that Cdk2 levels were decreased, in the presence of leflunomide, 48 hr after stimulation. These data further confirmed that leflunomide inhibited B cell progression through the S phase, We also present evidence that the addition of exogenous uridine reversed the antiproliferative activity of leflunomide. This indicated that leflunomide acted as a pyrimidine synthesis inhibitor, thereby inhibiting B cell proliferation and cell cycle progression.