One contributing cause of age-related immune system dysfunction is exposure to cytomegalovirus (CMV). Near everyone has it by the time they reach old age, and this persistent herpesvirus coerces ever more of the immune system's limited resources to uselessly battling it - the body cannot effectively clear CMV, but it continues to try, year after year. Immune cells that should be undertaking other, far more vital work are sidelined into the dedicated watch for CMV.
The best short term approach to this problem may be to adapt targeted cell-killing technologies developed for use against cancer and adapt them to destroy CMV-specific immune cells, based on targeting the distinctive surface chemistry of these cells. That would free up immune system capacity for more useful cells to emerge.
This study identified a novel, striking link between CMV-specific cellular immunity and vascular changes in older life. The vast majority of CMV-infected people had CMV-specific CD4+ T cells in their peripheral blood that displayed the hallmarks of iTregs and whose frequency was significantly associated with both mean arterial blood pressure and diastolic blood pressure in a linear regression model. The frequencies of CMV-specific CD8+ effector T cells were highly correlated with these regulatory-type CD4+ T cells and, likewise, significantly associated with mean arterial blood pressure and diastolic blood pressure. These observations point to a direct link between quantitative measurements of CMV-specific immunity and functional vascular parameters. These findings were not explained by confounders such as age, inflammation (ie, CRP level), BMI, smoking history, or use of antihypertensive medication.
In conclusion, our study provides new and compelling evidence of a quantitative link between CMV-specific cellular immunity and blood pressure or, indirectly, vascular stiffness in older age. Together, these findings may indicate that CMV has an important role in driving vascular changes in older life that ultimately affect survival. The level of cellular immunity to CMV might become an important target for intervention in the future, because it is doubtful that the huge CMV-specific T-cell expansions observed in some CMV-infected people are actually required to control infection.