Cytomegalovirus Infection and Memory T Cell Inflation

Abstract

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.