CD47 and death signaling in the immune system.

Receptor-mediated death signaling plays a critical role both in proper control of immune responses and in killing of target cells by T cells. In addition to the recognized death receptors which all belong to the tumor necrosis factor receptor family, recent studies suggest that also other cell surface antigens may be involved in apoptotic signaling in the immune system. New data on the Ig family member CD47 implicate a functional role of this molecule in growth regulation of lymphocytes and suggest that the antigen mediates cell death by activating a non-classical form of apoptosis. This mini review will focus on CD47 as a possible death receptor on lymphocytes and also summarize some of the current knowledge on death control in the immune system.