Cytokines Research Paper

INTRODUCTION:
The Immune System is a multipurpose defense system that has evolved to protect animals. The protective mechanism of organisms can be determined by the recognition of precarious stimuli followed by appropriate response in terms of activation of innate and adaptive immune responses. Immune function further depends on the biologic activities of numerous small glycoprotein messengers, termed cytokines. Originally discovered and defined on the basis of their crucial functional activities, cytokines are now defined primarily by structure. Typically, cytokines display extensive functional activities that mediate not only effector and regulatory immune functions, but also exhibit wider effects across an array of tissues and biologic

Initially, cytokines were called “lymphokines” to distinguish them from “monokines” in an attempt to classify these soluble factors by their primary sources but that nomenclature was short lived and yielded to “cytokines”. With the exception of the red blood cell, every cell can produce as well as respond to a cytokine. The field of cytokines came of age in the late 1970s with the introduction of molecular biological approaches that resulted first in the cloning of IFNs, initially IFN-β by Tada Taniguchi and IFN-α by both Charles Weissman’s group and David Goeddel’s colleagues. By the mid-1980s, there was a plethora of well-defined cytokines and cytokine receptors that could be unambiguously studied, using molecular tools, such as cDNA probes, and antibodies that had been produced to recognize the pure recombinant proteins. All this was a long way from the 1960s and 1970s, when all researchers had were many uncharacterized bioactivities in cell supernatants termed simply by activity, e.g., lymphocyte-activating factor, macrophage activating factor, and leukocyte pyrogen. All the tools available by the mid-1980s enabled researchers to assess the expression of cytokines in physiological and pathological

Although these other two terms continue to be used, they are misleading because secretion of many lymphokines and monokines is not limited to lymphocytes and monocytes as these terms imply, but extends to a broad spectrum of cells and types. For this reason, the more inclusive term cytokine is preferred. Many cytokines are referred to as interleukins, a name indicating that they are secreted by some leukocytes and act upon other leukocytes. Interleukins 1–25 have been identified. There is reason to suppose that still other cytokines will be discovered and that the interleukin group will expand further. Some cytokines are known by common names, including the interferons and tumor necrosis factors. Recently gaining prominence is yet another another subgroup of cytokines, the chemokines, a group of low-molecular weight cytokines that affect hemotaxis and other