GIF regulation of B cells and CD4 cells

描述(申请人提供)：一种名为GIF或MIF的细胞因子的功能很长一段时间都不清楚。然而，最近的研究表明，这种细胞因子在C60的翻译后修饰是与受体结合所必需的，并能够抑制B细胞Ig开关、BCR介导的抗原摄取以及从CD4细胞分泌IL-4。GIF-/-小鼠对T依赖抗原的抗体反应增强，与Ig亚型无关，但对T非依赖抗原的反应正常。与野生型细胞相比，GIF-/-小鼠的CD4细胞分化为Th2表型。静息状态下小鼠T、B细胞未检测到GIF受体，但经体外刺激后可在这些细胞上诱导出GIF受体。GIF受体是一种50-52 kDa的细胞表面蛋白。为了确定GIF的生物学效应是否通过GIF与其受体的相互作用而介导，我们将制备抗GIF受体的单抗，并克隆该受体的编码基因。为了确定这种细胞因子的靶细胞，将使用来自不同造血和非造血组织的细胞和mRNA样本来描绘受体的表达。为了阐明GIF在T-B协同过程中调节B细胞活化的作用，用HEL-OVA结合物在体外刺激MD4 BCR TG小鼠的HEL特异性B细胞和DO11.10 TCR TG小鼠的OVA特异性CD4细胞，无论是GIF+/+背景还是-/-背景。在同源T-B相互作用的过程中，将分析GIF的分泌、其受体的诱导以及与B细胞激活相关的事件。将分析GIF对BCR依赖的抗原摄取、运输和加工的影响。为了确定GIF在细胞因子产生和Th分化中的作用，我们将分析GIF受体的表达和GIF在T细胞激活时的分泌。调节Th分化的GIF的来源将通过过继转移实验确定，该实验使用来自GIF+/+和-/-DO11.10 TCRTG小鼠的CD4细胞和骨髓嵌合体结构。GIF抑制Th2分化和/或诱导Th1分化的机制将从STAT磷酸化和转录因子方面进行分析。GIF在调节Th2型炎症中的作用将在抗原诱导的哮喘小鼠模型中进行评估。这些实验将确定这种细胞因子在CD4T细胞介导的免疫反应中的作用。

DESCRIPTION (provided by applicant): The function of a cytokine called GIF or MIF has been unclear for a long time. However, recent studies have demonstrated that a posttranslational modification of this cytokine at C60 is required for the binding to the receptor and for the capability to inhibit B cell Ig switch, BCR-mediated antigen uptake, and IL-4 secretion from CD4 cells. GIF-/- mice displayed enhanced antibody responses to a T-dependent antigen regardless of Ig isotype but normal responses to a T-independent antigen. CD4 cells from GIF-/- mice differentiated toward a Th2 phenotype as compared with wild type cells. GIF receptor was undetectable in resting mouse T and B cells, but after in vitro stimulation the receptor was induced on these cells. GIF receptor appeared to be a 50-52 kDa cell surface protein. To determine whether the biological effects of GIF is mediated through the interaction of GIF and its receptor, anti-receptor mAb will be generated and the cDNA encoding the receptor will be cloned. To define the target cells for this cytokine, the expression of the receptor will be delineated using cells and mRNA samples from various hematopoietic and nonhematopoietic tissues. To clarify the role of GIF in regulating B cell activation in T-B collaboration, HEL-specific B cells from MD4 BCR Tg mice and Ova-specific CD4 cells from DO11.10 TCR Tg mice, either on GIF+/+ or -/- background, will be stimulated in vitro with HEL-Ova conjugate. The secretion of GIF, the induction of its receptor, and the events associated with B cell activation will be analyzed in the course of the cognate T-B interaction. The effects of GIF on BCR-dependent antigen uptake, trafficking, and processing will be analyzed. To determine the role of GIF on cytokine production and Th differentiation of CD4 cells, the expression of GIF receptor and the secretion of GIF upon T cell activation will be analyzed. The source of GIF that regulates Th differentiation will be determined by adoptive transfer experiments using CD4 cells from GIF+/+ and -/- DO11.10 TCR Tg mice and bone marrow chimera constructions. The mechanism by which GIF inhibits Th2 differentiation and/or induces Th1 differentiation will be analyzed with regard to Stat phosphorylation and transcription factors. The role of GIF in regulating Th2-type inflammation will be evaluated in the mouse model of antigen-induced bronchial asthma. These experiments will establish the role of this cytokine in CD4 T cell-mediated immune responses.