On the Aging Adaptive Immune System

An interesting fact about the adaptive immune system: the number of T cells in the body remains much the same across the entire lifespan, even after the supply of new T cells all but ceases in middle age. T cells are created as thymocytes by hematopoietic cells in the bone marrow, and then mature in the thymus. The supply of new cells from the bone marrow is negatively affected by age, while the thymus atrophies, active tissue becoming replaced with fat. Lacking replacements, the T cell population in the body becomes increasingly exhausted, senescent, and otherwise damaged. Many T cells become inappropriately specialized to persistent viral infections such as cytomegalovirus, leaving too few naive T cells to tackle new threats. Harmful subpopulations of T cell arise, connected with chronic inflammation, autoimmunity, and tissue dysfunction. The aging of the immune system is an important component of age-related degeneration. The adaptive immune system has the enormous challenge to protect the host through the generation and differentiation of pathogen-specific short-lived effector T cells while in parallel developing long-lived memory cells to control future encounters with the same pathogen. A complex regulatory network is needed to preserve a population of naïve cells over lifetime that exhibit sufficient diversity of antigen receptors to respond to new antigens, while also sustaining immune memory. In parallel, cells need to maintain their proliferative potential...
Source: Fight Aging! - Category: Research Authors: Tags: Daily News Source Type: blogs