Death and Dying in the Immune System

Abstract

Publisher Summary The phenomenon of physiological cell death involves the transformation of healthy cells to condensed apoptotic bodies. The dead cell corpse, with its characteristic morphology, is the end point of the process. The discussion presented in this chapter is an assumption that the hallmarks of this process reveal a common mechanism of dying. Issues of death (especially in the contexts of cell turnover and negative selection) have long been appreciated as central to immunobiology. As a result, physiological cell death has been extensively studied in lymphocytes. Although selective physiological death occurs among cells generally during ontogeny, lymphocytes are unusual in retaining susceptibility to a large variety of suicide inducers throughout their life cycle. The selective induction of physiological cell death in lymphocytes serves two distinct functions. The first, of course, is in central repertoire selection-in the initial and early elimination of functionally inappropriate clonal populations. The second and equally critical role of physiological cell death is in the dampening of immune responses. As demonstrated in studies of activation-driven cell death, the response of a lymphocyte to an antigenic stimulus is finite. A lymphocyte may exert effector function and proliferate in response to antigen, but by virtue of that response the cell is made susceptible to death upon further stimulation.