Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.
J Immunol. 2010 Sep 15;185(6):3285-94. doi: 10.4049/jimmunol.0900027. Epub 2010 Aug 20.
T cell activation and effector function is essential for robust immunity. Ag TCR signals are known to regulate T lymphocyte differentiation, but the mechanisms involved in this regulation remain unclear. Recent work has demonstrated that the Src family protein tyrosine kinase p56Lck specifically links TCR signaling to activation of the MAPK pathway through the function of its Src homology 3 (SH3) domain. The MAPK pathway is involved in T cell activation and has previously been implicated in Th2 immunity. We have used Lck SH3 mutant knockin mice (LckW97A) to investigate the potential role of this regulatory mechanism in T lymphocyte activation and effector function. Our results demonstrate that Lck SH3 domain function regulates activation of T lymphocytes as indicated by reduced IL-2 production, CD69 induction, and proliferation of LckW97A T cells following TCR stimulation. Biochemical studies confirm that activation of the MAPK pathway is selectively altered following TCR ligation in LckW97A T lymphocytes. Phospho-ERK induction is reduced, but phospho-phospholipase Cgamma1 induction and calcium mobilization are largely unaffected. Immunization with DNP-keyhole limpet hemocyanin, heat-killed Brucella abortus, or infection with Nippostrongylus brasiliensis demonstrates selectively impaired Th2 immunity with reduced serum levels of IgG1, IgE, and IL-4. In vitro studies show that LckW97A T cells can differentiate into Th2-type cells, but they form IFN-gamma-producing cells under conditions that normally favor Th2 development. These data indicate that the Lck SH3 domain controls T lymphocyte activation by regulating MAPK pathway induction and demonstrate a novel role for Lck in the regulation of Th2-type immunity.
T 细胞的激活和效应功能对于强大的免疫至关重要。已知抗原受体（TCR）信号调节 T 淋巴细胞分化，但这种调节涉及的机制仍不清楚。最近的研究表明，Src 家族蛋白酪氨酸激酶 p56Lck 通过其Src 同源 3（SH3）结构域的功能，特异性地将 TCR 信号与 MAPK 途径的激活联系起来。MAPK 途径参与 T 细胞激活，先前已被牵连到 Th2 免疫中。我们使用 Lck SH3 突变敲入小鼠（LckW97A）来研究这种调节机制在 T 淋巴细胞激活和效应功能中的潜在作用。我们的结果表明，Lck SH3 结构域功能调节 T 淋巴细胞的激活，这表现为 LckW97A T 细胞在 TCR 刺激后产生的 IL-2 减少、CD69 诱导和增殖减少。生化研究证实，在 LckW97A T 淋巴细胞中，TCR 交联后 MAPK 途径的激活被选择性改变。磷酸化 ERK 的诱导减少，但磷酸化磷脂酶 Cgamma1 的诱导和钙动员基本不受影响。用 DNP-钥孔血蓝蛋白、热灭活布鲁氏菌流产株或感染旋毛虫进行免疫接种表明，Th2 免疫选择性受损，血清 IgG1、IgE 和 IL-4 水平降低。体外研究表明，LckW97A T 细胞可以分化为 Th2 样细胞，但在通常有利于 Th2 发育的条件下，它们形成 IFN-γ产生细胞。这些数据表明，Lck SH3 结构域通过调节 MAPK 途径的诱导来控制 T 淋巴细胞的激活，并表明 Lck 在调节 Th2 型免疫中的新作用。
