CD28 and apoptosis

LH Boise, PJ Noel, CB Thompson - Current opinion in immunology, 1995 - Elsevier
Current opinion in immunology, 1995Elsevier
T-cell activation is initiated through the TCR-CD3 complex. This signal is not sufficient,
however, to sustain the activation of T cells, and can lead to a state of anergy or to cell death
[1]. A second, or costimulatory, signal is required to prevent these fates for the T cell and to
allow an immune response to occur. The second T-cell activation signal can be provided by
engagement of CD28 on the T cell with the B7 family of counter-receptors expressed on the
antigen-presenting cells (for reviews see [2-4]). This signal can lead to the enhanced …
T-cell activation is initiated through the TCR-CD3 complex. This signal is not sufficient, however, to sustain the activation of T cells, and can lead to a state of anergy or to cell death [1]. A second, or costimulatory, signal is required to prevent these fates for the T cell and to allow an immune response to occur. The second T-cell activation signal can be provided by engagement of CD28 on the T cell with the B7 family of counter-receptors expressed on the antigen-presenting cells (for reviews see [2-4]). This signal can lead to the enhanced production of lymphokines, such as IL-2, which are required for T-cell proliferation and/or T-cell help. Blockade of the interaction between CD28 and B7 will prevent transplant rejection as well as autoimmunity in animal models [5-10]. Although much attention has focused on the role of CD28, and the related receptor CTLA4, in the prevention of anergy, only recently has the role of costimulation in the prevention of lymphocyte cell death been closely examined.
In this review we will discuss the recent developments that demonstrate a survival enhancing function of CD28 ligation, through the increased production oflL-2 as well as the upregulation of Bcl-xL. In addition the role of CTLA4 in the negative regulation of T-cell activation, through the induction of apoptosis is reviewed.
Elsevier