CD27 is a co-stimulatory immune-checkpoint receptor, constitutively expressed on a broad range of T-cells (αβ and γδ), NK cells and B-cells. Ligation of CD27 with CD70 results in potent co-stimulatory effects. In mice, costimulation of CD8+ T-cells through CD27 promotes immune activation and enhances primary, secondary, memory and recall responses towards viral infections. Limited in vitro human studies support mouse experiments and show that CD27 co-stimulation enhances antiviral T cell immunity. Given the potent costimulatory effects of CD27, manipulating CD27 signaling is of interest for viral, autoimmune and anti-tumour immunotherapies. This review focuses on the role of CD27 co-stimulation in anti-viral T-cell immunity and discusses clinical studies utilising CD27 co-stimulation pathway for anti-viral, anti-tumour and autoimmune immunotherapy.

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