Abstract

Interactions between co-stimulatory ligands and their receptors are crucial for the activation of T cells, the prevention of tolerance and the development of T-cell immunity. It is now evident that members of the immunoglobulin-like CD28–B7 co-stimulatory family cannot fully account for an effective long-lasting T-cell response or the generation of memory T cells. Several members of the tumour-necrosis factor receptor (TNFR) superfamily — OX40, 4-1BB, CD27, CD30 and HVEM (herpes-virus entry mediator) — are poised to deliver co-stimulatory signals both early and late after encounter with antigen. The roles of these molecules in initiating and sustaining the T-cell response and in promoting long-lived immunity are discussed.

Author affiliations

1. Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA.
   Email: mick@liai.org