Soluble mediators in the immune system

The soluble mediators involved in inflammation and immune responses represent a diverse and incredibly complex biologic response network. This chapter focuses on families of cytokines that play key roles in initiating, maintaining, and/or resolving tissue inflammation, as well as in the function of the immune system, emphasizing their roles in the response to an allograft. It summarizes the properties of specific cytokines and their receptors and comments briefly on the roles of key cytokines known to play roles in allograft injury and protection. The acute phase cytokines stimulate a number of downstream inflammatory processes that contribute to graft injury. IFN-γ is by far the frequently observed cytokine produced by donor antigen-primed T cells during the rejection response, and exhibits immunoregulatory functions. In the absence of IFN-γ signaling, many T cell responses are of higher magnitude and longer duration indicating a function for IFN-γ in the homeostasis of adaptive immune responses.