The proposed studies involve investigation of various mediator substances produced by virus-infected cells, and by antigen-activated lymphocytes. The former have been defined as cytokines, and are similar in function to lymphocyte-derived lymphokines in that they behave as pharmocologic agents which affect various properties of inflammatory cells. Such actions include migration inhibition, chemotactic phenomena, and activating effects. We will explore the antigenic, physicochemical, and functional similarities of these two classes of mediators. Similarly, we will compare and contrast lymphokines produced by T and B lymphocytes. Both these studies will make use of anti-lymphokine sera we have previously prepared and characterized.