Introduction
Ageing is accompanied by a gradual decline in physiological functions, among which deterioration of the immune system, termed immunosenescence, has profound implications for human health. Immunosenescence refers to age-associated alterations in both innate and adaptive immunity that reduce host defence, impair vaccine responsiveness, and promote chronic inflammatory states. As global life expectancy continues to rise, understanding immune ageing has become a critical priority in health and biological sciences. [1]
Biological Mechanisms of Immune Ageing
Immunosenescence arises from cumulative molecular and cellular changes occurring over time. Thymic involution leads to a marked reduction in naïve T-cell production, limiting the immune system’s ability to respond to new antigens. Simultaneously, there is an accumulation of memory and senescent immune cells with reduced proliferative capacity. Age-related genomic instability, mitochondrial dysfunction, and altered cytokine signalling further contribute to immune dysregulation.
Innate immune cells such as macrophages, neutrophils, and natural killer cells also exhibit functional impairments, including reduced phagocytosis, altered chemotaxis, and diminished cytotoxic activity. Together, these changes weaken immune surveillance and delay pathogen clearance. [2]
Inflammaging and Disease Susceptibility
A hallmark of immunosenescence is inflammaging, a state of persistent low-grade systemic inflammation characterized by elevated pro-inflammatory cytokines. While acute inflammation is protective, chronic inflammation accelerates tissue damage and contributes to the development of age-related diseases such as cardiovascular disorders, metabolic syndrome, neurodegeneration, and certain cancers. Inflammaging thus represents a biological link between immune ageing and chronic disease burden. [3]
Clinical and Public Health Implications
The health consequences of immunosenescence are evident in increased susceptibility to infections, poorer outcomes following infectious diseases, and reduced efficacy of vaccines in older adults. Elderly populations also exhibit impaired immune-mediated tumor surveillance, increasing cancer risk. From a public health perspective, immune ageing poses challenges for disease prevention and healthcare sustainability, particularly in ageing societies. Organizations such as the World Health Organization emphasize healthy ageing and immune resilience as essential components of global health strategies. [4]
Future Perspectives and Conclusion
Emerging research integrating systems biology, immunogenomics, and artificial intelligence is improving the understanding of immune ageing at cellular and molecular levels. Interventions aimed at modulating immune function rather than simply stimulating it may help extend health span and reduce age-related disease risk.
In conclusion, immunosenescence is a fundamental biological process that shapes ageing, disease susceptibility, and therapeutic response. Continued interdisciplinary research is essential to translate insights from immune biology into effective health interventions for ageing populations.
