MEMBRANE ANCHORING AND FUNCTION OF CD16

Fc受体的结构和功能的知识是 这是理解免疫系统防御的基础。 在 人，三种类型的IgG Fc的结构和结合特性 受体（Fc-γ-Rs）。 在这些Fc-γ-γ RIII中， （CD16）已被证明是生理上重要的。 CD16是一种 50 - 70 kD的糖蛋白，在中性粒细胞上表达，自然杀伤 (NK)细胞、嗜酸性粒细胞和组织巨噬细胞。 体内研究使用 CD16单克隆抗体已经证明，CD16发挥主要作用， 从血液循环中清除免疫复合物。 CD16有两种不同的 膜锚;中性粒细胞中的磷脂酰肌醇聚糖（PIG）和 NK细胞中的多肽。 CD16在PNH中表达不足， 获得性造血干细胞疾病，其影响 PIG锚定蛋白。 该研究使用CD16阴性PNH 中性粒细胞检测CD16表达缺陷是否导致 异常的中性粒细胞功能，通过比较Fc依赖的功能， 正常和PNH中性粒细胞重建CD 16前后 表情 多肽锚定的CD16的功能 也将在相同条件下比较NK细胞上的表达。 这些研究将描述CD16缺乏对 中性粒细胞及膜锚对CD 16功能的影响。 这一建议也集中在建立稳定的转染子 表达/分泌各种形式的CD16。 因为没有细胞系 表达CD16的细胞，稳定的转染子将是一个很好的 用于进一步结构/功能研究的工具。 各种形式的CD16 将从这些稳定转染子的大规模培养物中纯化 并进行生化和功能表征。 的可功能 可以使用表征的纯化分子来定义这些分子的作用。 细胞功能中的受体。 将来，纯化的CD16可能 直接用于治疗慢性免疫性疾病， 血小板减少性紫癜和预防Fc介导的HIV和其他病毒 感染. 或者，完全了解其结构， 功能可用于设计治疗药物， 这些疾病。

The knowledge of the structure and function of Fc receptors is fundamental in understanding the defense of the immune system. In humans, the structure and binding properties of three types of IgG Fc receptors (Fc-gamma-Rs) have been described. Of these Fc-gamma-yRIII (CD16) has demonstrated to be physiologically important. CD16, is a glycoprotein of 50-70 kD and is expressed on neutrophils, natural killer (NK) cells, eosinophils and tissue macrophages. In vivo studies using CD16 monoclonal antibodies have demonstrated that CD16 plays a major role In clearing immune complexes from the circulation. CD16 has two distinct membrane anchors; phosphatidylinositol glycan (PIG) in neutrophils and a polypeptide in NK cells. CD16 is deficiently expressed in PNH, an acquired hematopoietic stem cell disease which affect the expression of PIG-anchored proteins. The proposed research uses CD16 negative PNH neutrophils to test whether the defect in CD16 expression leads to abnormal neutrophil functions by comparing the Fc dependent functions of normal and PNH neutrophils before and after reconstituting CD16 expression. The functional ability of polypeptide-anchored CD16 expression on NK cells will also be compared under the same conditions. These studies will delineate the consequences of CD16 deficiency on neutrophils and the influence of membrane anchor on the function of CD16. This proposal is also focused on establishing stable transfectants expressing/secreting various forms of CD16. Since no cell lines that express CD16 are available, the stable transfectants will be an excellent tool for further structure/function studies. The various forms of CD16 will be purified from large scale cultures of these stable transfectants and biochemically and functionally characterized. The functionally characterized purified molecule can be used to define the role of these receptors in cellular functions. In the future, a purified CD16 may directly be used therapeutically to treat diseases such as chronic immune thrombocytopenic purpura and prevent Fc mediated HIV and other viral infections. Alternatively, complete knowledge of its structure and function may be useful in designing therapeutic agent for treatment of these diseases.