兽医专业英语（扬州大学）作业.ppt

Cytokines 细胞因子 Cytokines are proteins secreted by the cells of innate and adaptive immunity that mediate many of the functions of these cells. Cytokines are produced in response to microbes and other antigens, and different cytokines stimulate diverse responses of cells involved in immunity and inflammation. In the activation phase of immune responses, cytokines stimulate the growth and dirrerentiation （分化） of lymphocytes, and in the effector phases of innate and adaptive immunity, they activate different effector cells to eliminate microbes and other antigens. Cytokines also stimulate the development of hematopoietic cells. In clinical medicine, cytokines are important as therapeutic agents or as targets for specific antagonists in numerous immune and inflammatory diseases. The nomenclature of cytokines is often based on their cellular sources. Cytokines that are produced by mononuclear phagocytes are sometimes called monokines, and those produced by lymphocytes are commonly called lymphokines. cells. With the advent of （随着…的出现 ）molecular cloning, it has become clear that the same protein may be synthesized by lymphocytes, monocytes, and a variety of tissue cells, including endothelial cells and some epithelial cells. Therefore, the generic term cytokines has become the preferred name for this class of mediators because many cytokines are made by leukocytes (e.g., macrophages or T cells) and act on other leukocytes, they are also called interleukins (IL). This term is imperfect, because many cytokines that are synthesized only by leukocytes and that act only on leukocytes are not called interleukins, for historical reasons, whereas many cytokines called interleukins are made by and act on cells other than leukocytes. Nevertheless, the term has been useful because as new cytokines are molecularly characterized, they are assigned an IL number (e.g., IL-1, IL-2; and so on) to maintain a santdard nomenclature. Cytokines are also increasingly used in clinical sit