The impact of aging on CD4⁺ T cell responses to influenza infection

CD4⁺ T cells are important for generating high quality and robust immune responses to influenza infection. Immunosenescence that occurs with aging, however, compromises the ability of CD4⁺ T cells to differentiate into functional subsets resulting in a multitude of dysregulated responses namely, delayed viral clearance and prolonged inflammation leading to increased pathology. Current research employing animal models and human subjects has provided new insights into the description and mechanisms of age-related CD4⁺ T cell changes. In this review, we will discuss the consequences of aging on CD4⁺ T cell differentiation and function and how this influences the initial CD4⁺ T cell effector responses to influenza infection. Understanding these age-related alterations will aid in the pharmacological development of therapeutic treatments and improved vaccination strategies for the vulnerable elderly population.