T cell activation is a complex process that requiresmultiple cell signaling pathways, including a primary recognition signal and additional costimulatory signals. TCR signaling in the absence of costimulatory signals can lead to an abortive attempt at activation and subsequent anergy. One of the best-characterized costimulatory pathways includes the Ig superfamily members CD28 and CTLA-4 and their ligands CD80 and CD86. The development of the fusion protein CTLA-4-Ig as an experimental and subsequent therapeutic tool is one of the major success stories in modern immunology. Abatacept and belatacept are clinically approved agents for the treatment of rheumatoid arthritis and renal transplantation, respectively. Future interventions may include selective CD28 blockade to block the costimulatory potential of CD28 while exploiting the coinhibitory effects of CTLA-4.
Bibliographical noteFunding Information:
This work was supported by National Institutes of Health Grants R37 AI040519 (to C.P.L.), U19 AI051731 (to C.P.L. and A.B.A.), and R01 AI104699 and R01 AI073707 (to M.L.F.).
Copyright © 2016 by The American Association of Immunologists, Inc.