Cytomegalovirus (CMV) infection in healthy individuals is usually asymptomatic and results in latent infection.
CMV reactivation occasionally occurs in healthy individuals according to their immune status over time. T cell responses to CMV are restricted to a limited number of immunodominant epitopes, as compared to responses to other chronic or persistent viruses. This response results in progressive, prolonged expansion of CMV-specific CD8+ T cells, termed ‘memory inflation’. The expanded CMVspecific CD8+ T cell population is extraordinarily large and is more prominent in the elderly. CMV-specific CD8+ T cells possess rather similar phenotypic and functional features to those of replicative senescent T cells. In this review, we discuss the general features of CMV-specific inflationary memory T cells and the factors involved in memory inflation.