Table 1. Effect of costimulatory molecules on virus-specific memory CD8+T cells.

The major costimulatory interactions that affect anti-viral memory CD8+ T cells are shown. The specific actions resulting from these interactions are diverse and can affect many aspects of memory CD8+ T cell responses.

Receptor	Ligand	Effect on memory CD8+ T cell
CD28	B7-1, B7-2	↑ expansion and IL-2 production82,84
PD-1	PD-L1/B7-H1, PD-L2/B7-DC	↓ proliferation of helpless CD8+ T cells91
CD27	CD70	↑ expansion with CD4+ T cell help and maintenance92,115–117
4-1BB	4-1BBL	↑ generation, maintenance and enhances proliferation95, 97,99,105 –108
OX40	OX40L	↑ survival and expansion in presence of CD4+ T cells 109–114
CD40	CD40L	↑ quality91,122
TRAIL receptors	TRAIL	↓ survival of helpless memory CD8+ T cells119,120